The Itron-Actaris B42R-3/4 is a versatile gas pressure regulator that can be integrated into HVAC systems and used with a variety of heating and cooling equipment. Utilizing a 1/2x9/16-inch outlet and a 3/4-inch Inlet Reducer Valve (IRV) it. For an efficient and reliable HVAC system, the Itron-Actaris versatile gas pressure regulator is the choice for optimal system performance. https://www.partshnc.com/b42r-34-itron-actaris-gas-regulator-internal-relief-valve