BP Wings vs BCD explanation

[SeaJay]

...That any advantage that a bp/wing has in streamlining has a net effect of about 50 psi savings.

I will maintain that the improved streamlining, the improved trim (so that the diver doesn't have to work to be horizontal) and the improved stability (so the diver doesn't have to work to keep his gear situated) all work together to have a significant drop in consumption.

Sure, one could ensure that they had a "regular BC" that had a plate in it... And one could use the trim pockets of their BC to get a bp/wing-like horizontal tendency... And one could customize their "regular BC" to come close to a bp/wing's streamlining... But why, when a bp/wing is so simple, so rugged, and priced much less than today's high line "regular BC's?" Add to that the bp/wing's ability to change bladders, the vast array of accessories available to those who have an available spot on 2" webbing, the fact that a bp/wing generally has many less "sizing" issues ("regular BC's" have to be sized, and thus limit resale... And in the meantime do not allow for a completely custom fit like a bp/wing does) and the difference in ruggedness between the plastic connectors THAT ARE CURRENTLY ON "REGULAR BC'S" and either the absence of, or the making of similar devices in metal... And I just can't see why one would choose a "regular BC" over a bp/wing. Availability, perhaps? Perhaps it's simply "the standard" to use a "regular BC." Perhaps it's to do with the fact that the manufacturers push new equipment and pretty colors year after year?

It just sounds like a marketing thing to me.

...And please note that none of the advantages I listed above have anything to do with whether you're wearing doubles or singles. They exist no matter how many tanks you dive with.

 

[Matthew]

Seajay,

A diver has to work to be horizontal when wearing a "regular" bc? A diver has to work to keep his gear situated? Then you have a skills problem. You seem to be implying that you can solve it by shifting to bp/wings.

I believe that any difference in air consumption between using a bc and a bp/wing, all other things equal, will be very minimal.

The reasons why one would choose a bc over a bp/wing have been repeated countless times in this board and other fora. Its not about colors or marketing. You simply refuse to see.


Matthew

 

[jplacson]

Well, my primary considerations when I chose a BP setup over a jacket were comfort, and the BP rig looks cooler. Nothing that had to do with performance since I love 'playing around' and flipping about while diving so the trim characteristics aren't that big a deal for me.

The comfort issue was a big deal for me since I hated the 'winter jacket' feeling of traditional BCs. It was a personal preference. But I feel it made the biggest difference for my diving experience... even over reg performance. I'm not saying I would want to have a bad reg... but between a normal reg, and a high performance reg... my diving experience improved... but not as much as when I shifted from a jacket BC to a BP rig.

Plus, the BP rig looks a lot sleeker... stupid reason, but it matters to me! Hey, it's all about the 'coolness' factor too ya know!

 

[MikeS]

I have a BP&W and a Seaquest Balance rear inflation, weight integrated BC. I dive with both depending on the circumstances, both have advantages.

Although this discussion is a bit of “beating a dead horse,” I felt compelled to weigh in since the biggest advantage/disadvantage of the BP&W was not even being discussed. The infinite adjustability of the B&W is a double edge sword.

The Balance is superior to a BP&W in ease of configuration. All you have to decide how much weight to put in the trim pockets and where to put the strap on the tank. Then you jump in, pull the straps tight and you’re ready to go. Changing exposure protection, no problem; add or subtract weight jump in pull the straps tight and you’re ready to go. The down side is that the trim adjustments are limited to the weight in the trim pockets and the tank strap location. In my case, with the 7 mil wetsuit I need to add ankle weights to the tank valve to get ideal trim. Additionally, the d-rings end up where they are, there’s no moving them and it’s not practical to add any.

The BP&W on the other hand is infinitely adjustable. There are many back plates to choose from varying in size and buoyancy. The harness is also infinitely adjustable. Most plate/wing combinations have several mounting options. Then there are single tank adaptors which come in various sizes and buoyancies. All this adjustability allows you to achieve trim that is just not possible with a traditional BC with it’s limited adjustability. The down side is that it’s a PITA to adjust. In my case switching from the dry suit to a 2.5 mil for the tropics not only requires harness adjustment but also requires removing the weighted STA and replacing the Fred T heavy plate with a standard plate.

So as a compromise I have my BP&W configured for use with the drysuit. It consists of a heavy Fred-T plate with a weighted STA and a Halcyon 36# pioneer wing. It’s adjusted how I want it and I don’t mess with it.

When the water and air are warm I prefer a wetsuit. When I use a wetsuit I use the Balance; it’s simply easier to adjust for different exposure protection. But I do not like the Balance with the drysuit as it’s adjustability as far as trim and d-ring location is too limited.

Mike

 

[-hh]

SeaJay once bubbled...
...That any advantage that a bp/wing has in streamlining has a net effect of about 50 psi savings.

The degree of savings from improved streamlining is going to depend on the dive conditions.

For example, any savings from streamlining will not be present at all on a pure drift dive profile.

I was not trying to claim that 50psi is THE number: I don't know what the actual savings would be for a particular dive profile, but more importantly, neither does anyone else! This is the objective quantified testing that no one has done.

My point is that the savings can be real, but still not be enough justify its adoption, because while real, it was not considered significant. I explicitily used 50psi as the Straw Man to illustrate this point. If you don't like 50psi, hypothesize a 100psi savings. Or 200psi. Whatever you wish. From there, you then estimate the "cost" to adopt that technology and the cost:benefit analysis. Since each one of us will have different decision criteria and threshholds, based on our individual needs, we may reach different conclusions even from the same numbers.

(BTW, also note that this process is not unique to BC's-vs-BP/W's: it can be applied to all elements of diving. Dive computers versus Tables are a good example).

I will maintain that the improved streamlining, the improved trim...and the improved stability...all work together to have a significant drop in consumption.

The challenge is in quantifying these variables so that you can prove causality (remember that corrolation is not causality), and then quantify your benefit for your cost:benefit analysis. If it is actually truely significant, it will then be self-evident.

When it comes to determining what is/isn't significant, another factor to consider is that we frequently improve our air consumption through personally develped skills and not with hardware changes. Personally, I'd place the definition of "Significance" somewhere around the 25% mark (because I've seen my SAC change "for no obvious reason" by this magnitude).

Most divers would probably consider an improvement in SAC from better skills to be "free" (because they're looking at their wallets). As such, how should this be factored into our cost:benefit analysis? FWIW, this does raise the question as to why we seem to be prone to looking for hardware solutions instead of skills...is it our contemporary cultural preferences for the "easy way" and "Instant Gratification"?

Sure...one could customize their "regular BC" to come close to a bp/wing's streamlining... But why, when a bp/wing is so simple, so rugged, and priced much less than today's high line "regular BC's?"

One possible reason is because the benefit isn't significant enough to merit the adoption costs.

For example, for the diver who already owns a BC, these additional costs include buying a BP/W to replace his existing one. If we assume a knowledgble and informed consumer and perform a cost:benefit analysis to help him to decide if he should or should not buy, what will the numbers show? Here's one such Straw Man:

- New Halycon BC/W, with all the trimmings: $500
- Sale of diver's existing used BC: $250

- Cost of a Generic dive (per hour of bottom time): $60
- Streamlining benefit: +10% (+250psi per AL80)

- Adoption cost: $500 - $250 = $250.
- Benefit per dive: 60min*10% = 6min

- Previous Cost per dive-hour: $60
- New Cost per dive-hour: {$60/(60+6min)}*(60min/1hr) = $54.55

- Cost savings per dive-hour: $60 - $54.55 = $5.45/hr
- Dive-hours until break-even: $250/$5.45 = 46

For your generic hardcore "every weekend" diver, the payback is on the order of ~5 months (assumes 10 hours/month). But for your generic vacation WWW recreational diver who does one dive trip per year (~20 dive-hours), that works out to a bit over 2 years until the BP/Wings "pays for itself" through additional bottom time gained.

Since all of these numbers can be changed, we can develop other scenarios. For example, if the savings really isn't this large (10% would be 250psi), the dives-until-breakeven becomes longer. Invoking my prior ~2% (50psi) number, it works out to 230 dives-to-breakeven, which for the same hardcore diver is ~2 years, and the same rec diver, ~11.5 years.

FWIW, note that this is a simple, first cut to get a rough order of magnitude handle on things: we've ignored a lot of lifecycle factors (present value of money, maintenance, etc), as well as assumed money as a convenient "bottom line" form of measurement.

... the difference in ruggedness between the plastic connectors THAT ARE CURRENTLY ON "REGULAR BC'S" and either the absence of, or the making of similar devices in metal...

Come on already: if you're going to continue to claim that something's dangerously unreliable for the application (here, recreational), you're obligated to prove your claim. You have a few anecdotal observations, but that's just the Numerator: you have no clue what your Denominator is.

For example, I've done a Reliability Analysis based on my objective firsthand data with QD's (Numerator & Denominator). They currently exceed 1000 hours MTBF (Mean Time Between Failure) at a 75% Statistical Confidence Interval.

If you want to express the same data as "Mean Dives Between Failure", that value is over 1200 dives @ 75% Confidence Interval.

...And please note that none of the advantages I listed above have anything to do with whether you're wearing doubles or singles. They exist no matter how many tanks you dive with.

Understood. Just please understand that "exists" is not the same as "significant".

If we can't come up with the hard numbers that quantify the streamlining benefit, then we have a hard time determining if "exists" also is "significant". We also have a problem in that claims of significant have no objective proof, which means that they fall into the realm of yet another "Marketing Ploy".

Which brings us again full circle: no data.


-hh

 

[SeaJay]

Matthew once bubbled...
Seajay,

A diver has to work to be horizontal when wearing a "regular" bc? A diver has to work to keep his gear situated? Then you have a skills problem. You seem to be implying that you can solve it by shifting to bp/wings.

Not exactly.

The point that I made was that bp/wings have different trim characteristics. There is no skill which can surmount a trim problem unless you fin and work to remain properly situated. You simply either fin (or use your hands) to get horizontal, or you address it from an equipment standpoint and change your trim through the proper placement of weight. That's it... There is no "skill" which you can develop to suddenly make your body balanced in the water column.

This trim issue is fixable using trim "band aids" like placing ankle weights on your tank valves... In some cases where not much trim weight is necessary, the pockets on some of today's better "regular BC's" are enough to get fairly good trim out of them. My point was, "why do that, when it's built into a bp/wing?"

I believe that any difference in air consumption between using a bc and a bp/wing, all other things equal, will be very minimal.

How do you know? Have you ever tried a bp/wing?

You simply refuse to see.

I do? Please read the article I wrote about the 30+ BC's I tested last year and how they stacked up against one another...

 

[SeaJay]

-hh once bubbled...


I was not trying to claim that 50psi is THE number:

Ah, my bad, then... That's what I thought you were saying. Sorry.

FWIW, this does raise the question as to why we seem to be prone to looking for hardware solutions instead of skills...is it our contemporary cultural preferences for the "easy way" and "Instant Gratification"?

Whoa, whoa, whoa... Just for the record, I am not implying that hardware will solve problems that are skill related... I'm implying that hardware solutions will solve hardware problems. The whole skill issue has never come into any of our discussions. For the record, I feel that diver skill is far and above more important than hardware... But I also feel that some of that skill is spent learning how to handle the hardware, in terms of proper setup and correct trim. My point is that some issues... Like trim, are BOTH skill and hardware issues.

...But let's not even get into the skill set issues... We can't even agree on anything regarding equipment... How would you and I possibly agree on skills?

One possible reason is because the benefit isn't significant enough to merit the adoption costs.

For example, for the diver who already owns a BC, these additional costs include buying a BP/W to replace his existing one. If we assume a knowledgble and informed consumer and perform a cost:benefit analysis to help him to decide if he should or should not buy, what will the numbers show? Here's one such Straw Man:

- New Halycon BC/W, with all the trimmings: $500
- Sale of diver's existing used BC: $250

- Cost of a Generic dive (per hour of bottom time): $60
- Streamlining benefit: +10% (+250psi per AL80)

- Adoption cost: $500 - $250 = $250.
- Benefit per dive: 60min*10% = 6min

- Previous Cost per dive-hour: $60
- New Cost per dive-hour: {$60/(60+6min)}*(60min/1hr) = $54.55

- Cost savings per dive-hour: $60 - $54.55 = $5.45/hr
- Dive-hours until break-even: $250/$5.45 = 46

For your generic hardcore "every weekend" diver, the payback is on the order of ~5 months (assumes 10 hours/month). But for your generic vacation WWW recreational diver who does one dive trip per year (~20 dive-hours), that works out to a bit over 2 years until the BP/Wings "pays for itself" through additional bottom time gained.

I completely agree.

Of course, you're assuming that someone already owns a "regular BC" and that there would BE an adoption cost. I suggest running the same numbers for the person who does not currently own a BC, but is instead purchasing one.

In the above example, you mention selling a used BC for $250. If that's the case, then it's reasonable to assume that new, that BC was sold for about double the used price... Or about $500... Which conveiniently is the price of most "better" "regular BC's." It's also conveiniently the price of a new Halcyon MC system, which includes one of the most reputable bp/wings on the market.

In that comparison example, notice the adoption costs: $0. That's all there is to it.

Your numbers are skewed towards someone who already owns a "regular BC." I'm sure I could skew the numbers as well if I assumed that someone already owned a bp/wing and was "making the switch" to a "regular BC."

After all, if it's to be a level playing field so to speak, then the playing field should be level.

...Of course, you're also doing a cost/benefit analysis... And some divers consider other factors to be more important when comparing life support equipment.

Come on already: if you're going to continue to claim that something's dangerously unreliable for the application (here, recreational), you're obligated to prove your claim. You have a few anecdotal observations, but that's just the Numerator: you have no clue what your Denominator is.

I never claimed them to be "dangerously unreliable for the application." I mentioned that I saw no benefit in them, and the possibility (you say the occurence is statistically rare, but I say that "rarity" isn't the point) of failure suggested that divers would be better off without them. You apparently feel that they make your dive more enjoyable. I feel that you can develop skills which render the breakable piece pointless.

...But I then followed it up with, "If they make your dive more enjoyable, then go for it... That is the point of diving, isn't it?" Heck, I couldn't care less if you use plastic pieces or not. If they work for you, then go for it. I don't think that my words are going to change your opinion of them, and I respectfully ask that you give me the same courtesy. We simply dive differently regarding plastic connectors.

For example, I've done a Reliability Analysis based on my objective firsthand data with QD's (Numerator & Denominator). They currently exceed 1000 hours MTBF (Mean Time Between Failure) at a 75% Statistical Confidence Interval.

Yes, but how big is your sample data? If you want to do a statistical analysis, then you know that a larger number of samples is much more accurate than a small one. Why not take a poll of 250 divers? Let's ask them how many dives they have and whether or not they've ever seen a broken connector. Then we can collect data and crunch it, and come up with real (number of dive)/(number of broken connector) data.

Lastly, I would argue that a 75% confidence interval is completely unreliable. That means that more than 1/4th of the time, your data has nothing to do with "real life." Statisticians know that a confidence interval of 90% or higher is what is really required to be "statistically significant," with a 95% or higher confidence interval really being a better guage.

...So I would argue that if you want to develop and cite actual statistics, we do it right and gather real data and calculate it correctly.

 

[-hh]

SeaJay once bubbled...

Whoa, whoa, whoa... Just for the record, I am not implying that hardware will solve problems that are skill related... I'm implying that hardware solutions will solve hardware problems. The whole skill issue has never come into any of our discussions. For the record, I feel that diver skill is far and above more important than hardware... But I also feel that some of that skill is spent learning how to handle the hardware, in terms of proper setup and correct trim. My point is that some issues... Like trim, are BOTH skill and hardware issues.

I agree that balancing out a rig (UW trim) is "99% hardware"; my point in mentioning skills is that good trim is nice to have, but it is not the objective of the dive: its merely the means to an end.

One of the 'means to an end' is a measure of dive quality such as a dive's bottom time duration (there's others too). Good trim contributes to this by lowering the diver's level of effort, which reduces his air consumption, which allows for the longer dive. Ditto for streamlining.

But skill also clearly plays a role too, and in the context that a longer dives is of greater value, if someone can go spend $50 to take a Yoga class to learn to relax and this drops their SAC by 20%, or they can spend a similar $50 on some hardware widget that has the same net effect, then we should view this as a viable alternative...

The direction I'm going with this is that there are things other than just hardware that really should be considered when looking for both solutions as well as when assessing what is/isn't significant. For example, if simple practice will let a novice rec diver improve his air consumption by ~50%, should we encourage him to go dive more, or to immediately go buy a ~50% larger tank?

...and if there's a buch of "50 percenters" out there, its not really worth our time or effort sweating over the small stuff. This is where we have to figure out what is/isn't significant for our needs, and lacking objective data on things like the real effect of gear streamlining makes this a fiction instead of a science. Sure, there's some art thrown in there too...we want to look good

(cost:benefit)
Of course, you're assuming that someone already owns a "regular BC" and that there would BE an adoption cost. I suggest running the same numbers for the person who does not currently own a BC, but is instead purchasing one.

I agree, although I will point out that most divers considering a BP/W are existing divers with existing equipment and not novices straight out of the gate with no equipment.

In the above example, you mention selling a used BC for $250. If that's the case, then it's reasonable to assume that new, that BC was sold for about double the used price... Or about $500... Which conveiniently is the price of most "better" "regular BC's." It's also conveiniently the price of a new Halcyon MC system, which includes one of the most reputable bp/wings on the market.

The beauty of the cost:benefit process is its flexibility: we can also take the novice diver with no gear and determine the benefit of him spending $500 for a BP/W or a "good BC" versus dropping only $200 for a no-frills BC (eg, TUSA Liberator, etc). Of course, the hard part is coming up with the numbers that quantify each system's benefit (data, again).

(MTBF):
...Yes, but how big is your sample data?

That can be mathmatically determined from the information already provided by those that know how to...

...but to save you the math, I'm working from ~1485 hours demonstrated with 0 observed failures.

Why not take a poll of 250 divers?

Because what is known within statistical circles as a "Self Selecting Sample", which invalidates the data collection. There are ways around this, but they tend to be laborious.

Lastly, I would argue that a 75% confidence interval is completely unreliable. That means that more than 1/4th of the time, your data has nothing to do with "real life." Statisticians know that a confidence interval of 90% or higher is what is really required to be "statistically significant," with a 95% or higher confidence interval really being a better guage.

I disagree.

First, the application of any Confidence Interval means that we are not dealing with a mere point estimate.

Second, the selection of the Confidence Level's value depends on the application context, including the duty cycle, opportunity for servicing, duration of service and the severity of a discrete failure. This isn't a mere "Student t" test. Particularly since we already accept a biannual replacement of webbing on the BP/W design alternative, applying a high Confidence value lacks justification.

FWIW, most people don't understand statistical Reliability and Confidence. For example, to prove a Reliabilty of higher than 50% (classical coin toss) at a 95% confidence, you must flip 5 heads in a row.

Third, if you really want to see a higher CI, the MTBF is still a quite respectable 644 hours @ 90% Confidence. FWIW, this is just shy of an Reliability of 99.8% @ 95% Confidence (which requires 1498 hours).

Fourth, demonstrating a high Reliability at a high Confidence becomes extremely consuming. For example, for demonstrating R=0.999 @ 95% C, you need to demonstrate zero (0) failures out of 2,996 trials.

The basic rule of thumb for 95% confidence is zero failures for triple the Reliability that you want (need) to demonstrate. So if you want no more than a "1 in a Million" chance of failure, you need to test it ~3 million times (for those who care to know, the exact value is 0 for 2,995,730 trials).

...So I would argue that if you want to develop and cite actual statistics, we do it right and gather real data and calculate it correctly.

Already done. My data is from a trusted source, and the first set of numbers were calculated from Max Bamdad's Palm OS software program, "MTBF". The latter set of numbers are straight from Appendix C of Bulfisch's "Reliabilty Handbook".


-hh

 

[SeaJay]

-hh once bubbled...


I agree that balancing out a rig (UW trim) is "99% hardware"; my point in mentioning skills is that good trim is nice to have, but it is not the objective of the dive: its merely the means to an end.

I enthusiastically agree.

One of the 'means to an end' is a measure of dive quality such as a dive's bottom time duration (there's others too). Good trim contributes to this by lowering the diver's level of effort, which reduces his air consumption, which allows for the longer dive. Ditto for streamlining.

But skill also clearly plays a role too, and in the context that a longer dives is of greater value, if someone can go spend $50 to take a Yoga class to learn to relax and this drops their SAC by 20%, or they can spend a similar $50 on some hardware widget that has the same net effect, then we should view this as a viable alternative...

The direction I'm going with this is that there are things other than just hardware that really should be considered when looking for both solutions as well as when assessing what is/isn't significant.

Oh, I completely agree with that as well. In most cases I've seen, the problem isn't the gear at all, but lack of skill. I agree that this should - first and foremost - be addressed before making any gear configuration changes. We could talk about the reasons for this, but I think that you and I agree on this and I think that each of us could list about a dozen reasons.

(The sample size) can be mathmatically determined from the information already provided by those that know how to...

It was a rhetorical question, -hh... I'm fully aware of how to calculate sample size.

My point was that you have ONE set of sample data. Sure, there's ~1485 hours demonstrated... But that's hardly an unbiased sample.

If you really want to do this scientifically, then you'd have to collect a variety of true sample data.

First, the application of any Confidence Interval means that we are not dealing with a mere point estimate.

Second, the selection of the Confidence Level's value depends on the application context, including the duty cycle, opportunity for servicing, duration of service and the severity of a discrete failure. This isn't a mere "Student t" test. Particularly since we already accept a biannual replacement of webbing on the BP/W design alternative, applying a high Confidence value lacks justification.

I'm not going to get back into that debate with you, but I will remind you that if you're going to collect statistical data to prove a point about whether the failure of plastic connectors is "significant," then I also suggest that you gather statistical evidence to prove your notion of biannual webbing replacement... And then calculate whether or not your findings are "significant." I'm of the opinion that any plastic connector failure is significant, since you can use skills to nullify their use. I also feel that webbing replacement - which is not performed biannually - is done largely for cosmetic reasons alone and is insignificant. You feel the opposite is true. Those are the facts - we disagree on the rest, and I'm not going to debate them again with you.

FWIW, most people don't understand statistical Reliability and Confidence. For example, to prove a Reliabilty of higher than 50% (classical coin toss) at a 95% confidence, you must flip 5 heads in a row.

Third, if you really want to see a higher CI, the MTBF is still a quite respectable 644 hours @ 90% Confidence. FWIW, this is just shy of an Reliability of 99.8% @ 95% Confidence (which requires 1498 hours).

Fourth, demonstrating a high Reliability at a high Confidence becomes extremely consuming. For example, for demonstrating R=0.999 @ 95% C, you need to demonstrate zero (0) failures out of 2,996 trials.

<snip huge, pointless lesson on statistics>

-hh, you stated a claim: That plastic connectors breaking aren't statistically significant, yet you've only gathered information from one biased source - yourself. I'm simply saying that if you want to prove your point, you first need to gather many more samples from unbiased sources.

My data is from a trusted source, and the first set of numbers were calculated from Max Bamdad's Palm OS software program, "MTBF". The latter set of numbers are straight from Appendix C of Bulfisch's "Reliabilty Handbook".


-hh

So what? I'm not arguing that your figures aren't mathematically cruched correctly... In fact, I think that they are. However, what you've fed into them in the first place isn't a fair sample.

...And to the best of my knowlege, no, that data has NOT been collected already.

 

[paulwlee]

SeaJay once bubbled...
This trim issue is fixable using trim "band aids" like placing ankle weights on your tank valves... In some cases where not much trim weight is necessary, the pockets on some of today's better "regular BC's" are enough to get fairly good trim out of them. My point was, "why do that, when it's built into a bp/wing?"

Seajay, you have to remember that for most people in the world 6lbs is a small fraction of their total required weight. Even when using a SS BP, the same type of methods you call "band aids" may be needed attain good trim. Things such as getting different tanks, or placing trim pockets, etc. (I don't want to buy another plate or a weighted STA.)

As an example, I have good trim with my previous BC and with my new BP/wing. (I can stay in that GUE good trim with no movement.) However, during the DIRF class I took this past weekend, I switched my Atomic Split fins(which are neutral) to Jet fins (negative) which screwed up my trim to be slightly feet heavy. I countered this with keeping some air in my drysuit boots, but this creates problems during ascent/descent. So I was less than optimal and had to expend some effort at maintaining good trim throughout the dive.

I need 30lbs total with an AL80, so with a 6lb SS plate, I still need 24lbs on my belt. I am getting a new steel tank, and will be able to drop 5~6lbs from the belt and hoping that will fix the trim issue with the negatively buoyant fins.

That was just an effort to illustrate how BP/wings do not automatically give you good trim.

BTW Seajay, I had a blast with the DIRF class! Learned to do some things better, got to see myself underwater, saw how great the components of DIR fall in place together etc. I especially liked what I can do with the canister light. Now I need to go and get one for myself. More $$$$...