The 1/2" Apollo Model RP4ALF Reduced Pressure Principle Backflow Preventers prevent contamination of the potable water supply due to backsiphonage or backpressure from substances that are health or non-health hazards. The bronze body is configured with individually-accessible top-access check valves including topmounted test cocks. The relief valve is bottom-centered with a separate access cover. The replaceable seat rings consist of glass-filled Noryl and the reversible seat discs are silicone rubber. The Apollo domestic shut-off ball valves have stainless steel handles. Made in America with a five-year Apollo factory warranty!