Fluval Mini Pressurized 20g-CO2 Kit - 0.7 ounces Mini Pressurized CO2 Kit for small, planted aquariums Regulator valve effectively controls CO2 output Bracket secures CO2 cartridge to the side of the aquarium Kit includes: regulator valve, cartridge bracket, disposable CO2 cartridge, hose, and internal CO2 diffuser Complete pressurized CO2 system