Get more shots with the larger 24oz Size! CO2 tanks are made from high quality aluminum that's light but tough! A 24 oz tank fill will get you about 1200 shots. All tanks have an industry standard pin valve that will fit any standard ASA. The pin valve uses a standard #10 o-ring (included) which costs pennies to replace. Tanks are shipped empty to comply with safety standards. Can be filled at fields or sporting good stores just about anywhere!