The CO2 cartridge 88g is designed for air rifles with CO2 drive. The cartridge is screwed onto a spike in the gun that pierces the throat. The number of shots depends on the model of the air gun, the cartridge is disposable and cannot be refilled. It is necessary to shoot the cartridge and not leave it under unnecessary pressure in the weapon. So, if you know that you will not be shooting the air gun for a long time, unscrew the cartridge so that you do not unnecessarily reduce the life of the sealing rings. Always unscrew the cartridge only when it is empty, if it is full, the gas will quickly hiss and can cause frostbite or otherwise damage the weapon. The cartridge is intended for CO2 air rifles of all manufacturers (Crosman, Umarex, Walther, etc.)