DR. moss 3/5/9 Spiro glass Co2 Diffuser -for Aquarium Atomizer Solenoid Regulator live moss plants . The high efficiency of diffusing carbon dioxide. CO2 bubble counter is built in this device. Easy to install and use, with no extra power required. Suitable for tanks 15 - 50 gal (60L - 200L) Suction cup (free) x2