Back-Up Ring, For Use With Acorn Comby, Acorn Showers, For Use with Series Acorn Auto Cloz Valves for Capitol/Apex/Classic Showers, Acorn Self-Cloz(R) Valves for Comby Units, Nitrile Rubber, Acorn Wash-Ware(R), Size 3/8 in ID x 1/2 in OD, Wash Fountain Gaskets and O-Rings, O-Rings, Package Quantity 10