Ista CO2 Basic Diffuser Set provides many aquarists with the perfect introduction to CO2 plant fertilization. Every planted aquarium benefits from adding CO2 to assist with photosynthesis and they will see a marked improvement in plant growth by using it. This set contains 4 items a diffuser check valve hose and a CO2 disposable canister. Recommended for nano and small aquariums up to 100 litres.