The Ista CO2 Controller with Solenoid, Bubble Counter & Check Valve is ideal for use in any freshwater planted aquarium with a CO2 injection system. This controller will ensure that your lush aquatic paradise will be accurately and reliably dosed with CO2 to promote the healthy, robust growth of your plants. Including a dual-gauge with an easy-to-read display, you can rest assured knowing exactly how much CO2 is entering your aquarium, and how much is remaining in the cylinder. Made of high quality stainless steel, this nifty controller is rust-poof and has been designed for use with face-side CO2 cylinders! This particular model is conveniently side-mounted onto the CO2 cannister and includes a solenoid, permitting it to be used with timers or other devices. A flash light indicator, bubble counter, and a safety valve has also been included. Absolutely no tools are required for installation!