Order the optional Keg Cap™ and turn your DrinkTanks Growler into a personal keg. This will keep your beer fresh to the last drop. This set comes with a cap, CO2 injector, and two threaded 16 gram CO2 cartridges.Item Specifications: CO2 injector & 2 threaded 16 gram CO2 cartridges Compatible with DrinkTanks Growlers only Does not include DrinkTank – must be purchased separately.