Suitable for residential, commercial, industrial, irrigation, marine and fire protection applications, Prevents the reverse flow of water, gases or other substances into the distribution system of the potable water supply, Pressure differential relief valve between two independent spring-loaded ""Y"" type center guided check valves complete with two full port ball valves and four ball valve test cocks, Noryl replaceable seats and silicone rubber check discs, Entire unit serviceable in-line, Temperature range 33F to 180F, Maximum pressure 175 psi, Listed ASSE 1013, AWWA, Size: 1"", SKU: HMREX1647