Lemonade once bubbled...
The one that hooks up in-line with the inflator... Was trying to eliminate an extra hose. Bad idea... A big, fairly heavy piece of gear hanging on the inflator... What was I thinking?!
Luckily the thing got squashed by a tank the second day (I swear it was not done on purpose ), and I didn't have to find an excuse to throw it away!
Genesis Sidekick, Scuba Pro Air 2, Buddy Auto Air, . .
All of these devices do the same thing surely, and are hardlly heavy? They are there as an alternative air source for the diver himself to use in those uncommon emergencies. In my opinion (for what its worth) combined with a top-of-the range main reg with a 2 metre LP hose for your out-of-air buddy to use, if necessary, this is surely the most ergonomically and finacially efficient set-up available.
I do not see the point in having another expensive reg at the end of yet another hose (in addition to the power inflator) since whenever it is needed there is only one way the diver or buddy pair should be heading and that's towards the surface?
Some of the advertising blurb reads as follows;
No need to drag that extra octopus hose around anymore. Since it's located right next to your power inflator, it is much easier to locate in an out of air emergency. You get one less hose and more function. I can't stand it when you jump in off the dive boat and your dangling octopus hits the water wrong and free flows your air away. The Genesis Sidekick stays close to you and is specially tuned to resist those unwanted free flows.
OK that was hype but like all such "reserve parachutes" there is no need for a snap shackle, suicide clip or similar, to mount the octopus in a position where it can easily be found and disconnected by my buddy before it can be used. In the buddy check I ensure he knows he has only to help himself to my main reg and guess where that will always be?
My Buddy Auto air breathes reasonably well down to more than 40 meters. OK its not anyhere nearly as good as my Apex T100 main reg but it is there for me to use in emergencies only and my set up ideally suits the type of diving I currently do.