Throw out your last disposable CO2 cylinder, and move forward with the V3. No more need for costly, disposable cartridges. This tiny, revolutionary regulator is designed to fit your preferred CO2 tank size. It easily installs on CGA-320 cylinder valves, without the use of a wrench. The Atomic CO2 Regulator V3 is designed specifically for use with our Atomic CO2 diffusers. Excellent for the beginner enthusiast or the planted tank professional seeking a sleek, compact, superior quality regulator. It features a fixed working pressure, precision needle valve and German-engineered solenoid.