The Standard Repair Kit is compatible with the 8”-10” Model 350A, 375, and 475, as well as the 8”-12” Model 350 and 450 Double Check Backflow Preventers. Repair Kit components conveniently include two Check O-Rings, twelve Poppet Bolt O-Rings, and two Seal Rings. Repair Kits are sold as accessories for quick and simple repair needs, providing long-lasting protection from both backsiphonage and backpressure of polluted water into the potable water supply.