This could change SCUBA as we know it.

[Gargamel]

Originally Posted by August

Again though, oxygen is deadly at depth. Unless there is a way to add helium or other inert gas the use of this gizmo would be limited to 15' or less.

It's almost useless, given your point, for recreational divers. Air is 22% O2, 75% N2, and 2% CO2, plus some other rubbish (I'm off with those numbers, i just forget the exact amount of N2). If you remove the O2, you're only saving 22% volume in compressing the air you'd have to mix. The expense of doing that for a rec diver is not worth it, when a tank of compressed air is almost free. Heli-ox though..... It'd save ya a whole tank IIRC.