My Buddy has his as a secondary necklace reg... its low profile, quite small and can be used anyway up... He likes the idea.
Although he tried it at 30m and was surprised at just how badly it breathed compared to his ATX50.....
Below 30m I would think you'd be ok... but as an octopus I'm not sure...
If I was out of air and needed lots quick and you handed me one of them.... then it would be a big shock to you, that I took the one out of your mouth....
