The 1" Rubber Repair Kit is compatible with the 1” Model 375 and 375XL Reduced Pressure Principle Backflow Preventer. Repair Kit components include one Sleeve O-Ring, one #1 Check Seat O-Ring, two Check Seal Rings, one #2 Check Seat O-Ring, one Housing Inlet O-Ring, one Housing Outlet O-Ring, one Relief Valve Cover O-Ring, one Relief Valve Seat O-Ring, one Relief Valve Seal Ring, one Diaphragm, and one Relief Valve Stem O-Ring. The accessories within the kit allow you to speed up repairs, while lowering maintenance costs and extending the product life. The Zurn Wilkins portfolio offers long-lasting protection from backsiphonage and backpressure of contaminated water into the potable water supply.