The Umarex CO2 Adapter allows airgun shooters to use two 12 gram CO2 cartridges in place of one 88 gram tank on most 88 gram CO2 powered airguns, like the Umarex AirJavelin, CX4 Storm and Umarex 850M2, . 12-gram CO2 cartridges are much easier to find in retail stores than the 88-gram tanks and they also offer shooters more flexibility, especially when only wanting to take a few shots. Prevents wasting unused portions of an 88-gram cartridge.