0122613 - 3 In Cast Iron Reduced Pressure Zone Backflow Preventer Assembly, NRS Shutoff, Lever3 In Cast Iron Reduced Pressure Zone Backflow Preventer Assembly, NRS Shutoff, Lever Handles This 3 inch lead free reduced pressure zone backflow preventer assembly is designed to prevent the flow of polluted water from entering into the potable water supply due to backsiphonage and or backpressure in accordance with national plumbing codes and water authority requirements. Its compact modular design facilitates easy maintenance with a single access