Maxitrol 325-5-1/2-12A39 1/2" Gas Pressure Regulator is used to regulate a constant outlet pressure in HVAC systems. It is capable of regulating gas flow with a maximum inlet pressure of 5 PSI, and maintains outlet pressure 4" to12" WC. This regulator has a built in vent limiter for safety purposes and to prevent venting and to operate efficiently. It is used as an ideal HVAC componen... https://www.partshnc.com/325-5-1-2-12a39-maxitrol-maximum-inlet-w-vent-limiter-4-12-1-2-5psi