Another option is the 14 oz hydration bladder distributed by Deep Sea Supply (https://www.deepseasupply.com/index.php?product=55). I asked about these a couple of months ago and few people had tried them. One respondent said he didn't like the plastic taste of the water. I bought one ($22) and I like it. But, it is configured for use primarily with doubles. The biggest issue, as with camelback-type devices, is that you take your reg out of your mouth, suck in water from the tube, swallow, and put the reg back in. Not a problem, just one point of consideration when comparing the SCUDA to these type of devices. Personally, I find it easier than trying to swallow with a larger (second stage) mouthpiece in my mouth, as stevead mentioned, but that is just me.