I tried it once to see how many breaths I would get out of it if I need it. I mostly keep it with my fire department turn outs in case I need to get to a submerged car quick. I can get between 35 and 45 breaths on it depending on exertion. I used it once to check a submerged car and fortunately everyone had been thrown out. I normally carry a 40cu ft pony bottle on my recreational diving and had a freeflow on a rental regulator that a buddy used and jammed the pony reg in his mouth. It works fine. I also screwed up once and didn’t monitor my air close enough and used the pony to finish a safety stop.