This total rubber parts kit is used for replacing or repairing the relief valve assembly on a 2 1/2 and 3 inch reduced pressure zone assembly 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 check disc, cover O-ring, sleeve O-ring, piston O-ring, RV disc assembly, diaphragm, piston seat and lubricant.