Series LF957RPDA, LF957NRPDA, LF957ZRPDA reduced pressure detector assembly backflow preventers provide protection to the potable water system from contamination in accordance with national plumbing codes. The reduced pressure detector assemblies are normally used in health hazard applications to protect against backsiphonage and backpressure. The Watts LF957RPDA, LF957NRPDA, LF957ZRPDA are used to monitor unauthorized use of water from the fire protection system. They feature Lead Free* construction to comply with Lead Free* installation requirements.