Co2 cartridges are mostly used with our range of airsoft co2 pistols. one of the benefits of buying a co2 bb gun is that the co2 capsules will work better in cold weather than the green gas versions also they are easy to load into the guns. we will beat any other UK price on co2 cartridges. We have a great range with Capsules from Remington ASG Umarex and Cybergun. 12g co2 capsules are the mostly used with our guns the bigger 88g capsules are for air rifles.