The Red Sea CO2 Pressure Regulator & Needle Valve is designed specifically for aquarium use, the Pressure Regulator and Needle Valve are independent units connected by low-pressure CO2 tubing. The high precision needle valve is designed to be mounted on the side of the aquarium enabling easy access for regular flow adjustment or complete shut off. Once assembled and set to the desired working pressure the CO2 Cylinder/Regulator can be located out of site, behind or under the aquarium. Easily upgradeable for automatic control with an in-line solenoid control valve. Please look at our CO2 System Info page for a complete list of products needed for a complete CO2 setupEasy to read high and low pressure gaugesIntegral pressure relief valveIndependent needle valve -- stable flow rate from 4 bubbles per minute