Thank you Tira! That gives me exactly what I wanted to know.The EnSet systems will run on Co2. I do use this method at shows so I don't have to lug a compressor. However, it will be expensive if you use it in the shop every day and don't use a compressor. I get about 1.5 days off a 5 lb. Co2 bottle with people using it all day at a show. The faster the machine goes the more air (or Co2) it chews through. The input pressure for either into the machine is about 90 psi.