Series 4000SS Reduced Pressure Zone Assemblies prevent the reverse flow of polluted water from entering into the potable water supply due to backsiphonage and or backpressure. It consists of a stainless steel body construction with stainless steel internal parts. The bottom-mounted relief valve is located between the two check valves, making it suitable for installations against an outside wall. Series 4000SS has a compact design with a short lay length, ideal for retrofit installations. The 4000SS is designed for health hazard applications. Check with local water authorities for installation requirements. Maximum Working Pressure: 175psi (12.06 bar).