This total rubber parts kit is used for replacing or repairing the relief valve assembly on a 4 inch lead free reduced pressure zone assembly series 909 used to prevent the reverse flow of polluted water from entering into the potable water supply due to backsiphonage and or backpressure. This kit consists of a diaphragm, two molded disc assemblies, two seat O-rings, RV O-ring, two piston O-rings, RV stem O-ring, flow tube O-ring and cover O-ring.