Ceramic disc valving is an innovative water control system found in each American Standard faucet. Each time you use one of our faucets, two discs control water flow by gliding back and forth in an airtight seal. American Standard's Ceramic Disc Valves are smooth and almost as hard as diamonds. The valves are unaffected by temperature extremes, sand, rust or hard water conditions. American Standard is the only faucet manufacturer to engineer and produce our own ceramic discs, ensuring complete quality control. Extensive life cycle testing assures that each valve will survive more than 1.5 million uses. With ceramic disc valving, American Standard guarantees a lifetime of drip-free and maintenance-free performance.