With due respect to the Rescuean and the OP, if you're going to buy something, why not an emergency O2 kit? I think this invention is great, but I'd be more interested in having the requisite O2 available. Medical O2 is an essential part of a divers kit. Instructors are required to have it available during training, most dive boats I've been on have it. I don't dive without it. Perhaps this is a cost benefit thing, but I don't try to save money on emergency equipment. The best thing to have available is 100% O2, why settle for less?