12 Gram CO2 cartridges are generally used as a gas source for airsoft guns and paintball pistols. The 12g cartridges that we sell are compatible with all the paintball pistols offered on our website. Each cartridge will provide about 15-20 shots depending on the paintball marker. You can also use a 12g CO2 cartridge in a standard size paintball gun. This is achieved through the use of a 12g adapter. Although a standard size paintball tank is the best air source for powering your paintball gun, a 12g adapter is an invaluable tool to use on the field should you run out of air in our full size tank. Simply slide the 12 gram cartridge into the adapter and screw the adapter into your asa to finish your game!