Premium AQUATEK CO2 Regulator with Integrated COOL TOUCH Solenoid Cool-touch, industrial solenoid design; Brass constructions for long-lasting durability and dependability Precision needle valve for fine tuning release of CO2; Precision output working pressure adjustment knob: 140 PSI Max Includes bubble counter with integrated check valve Compatible with most high density tubing Compatible with most CO2 atomizer and diffuser