Watts 957NRPDA BFG CFM FS 4 Part of the 957RPDA Series Window Well Cover This 1 1 2 inch lead This 1 1 2 inch lead free reduced pressure zone backflow preventer assembly with its exclusive design incorporating the patented air inchand water out principle for protection during an emergency condition prevents the flow of polluted water from entering into the potable water supply due to backsiphonage and or backpressure Specifications Kit Type Complete Rubber Parts Kit Lead Free YES Product Group BACKFLOW KITS UPC 098268384321 When activated through an add on sensor connection kit Alert features available with add on sensor connection kit