The reason I'm looking for the high rpessure is the Airwolf looks for 230. My local sub-aqua club (15 miles away) can fill to 210/220 BAR, and I took the bottle to them to fill. Once hooked up to the Airwolf, pressure only rose to 185 before the two evened out, so I did the rest by pump. It looks like thr 300 BAR fills are much further afield, and if I can only get a few fills from a huge bottle then I'm questioning the merit. At present I've only a 3L botle but would be happy to go to 12L or even 15L if it made sense.