This 1-1/4 to 2 IN Complete Rubber Parts Replacement Kit is Used For Repairing The Parts to The Relief Valve 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 Two Check Assembly O-Rings, Two Disc Assemblies, One Cover O-Ring, One RV Diaphragm, One RV Seat O-Ring, One Sensing Passage O-Ring, One Diaphragm Plate O-Ring, One RV Lower Stem O-Ring, One RV Upper Stem O-Ring, One RV Disc Assembly And One Bleed Screw O-Ring. | Watts | 0887280