Be sure of proper fit and seal with genuine powerlet 12-Gram CO2 forty pack of cartridges by Crosman. Exacting tolerances ensure consistent performance in virtually all gas-operated guns. We can not ship CO2 using air services. Please consider this when you choose a shipping method. Crosman invented the CO2 powerlet and is the recognized leader in this field. Put Crosman 12-Gram CO2 powerlets in any air-gun that uses 12-Gram CO2 cartridges.