Ensure your toilet works properly with this Master Plumber toilet disc. Made of rubber, this disc is durable and stays in place after installation. Its flexibility prevents breaks and cracks for structural stability. This toilet disc fits #5 American Standard flush valves. Its circular shape ensures an accurate fit on a flush valve to prevent leakage. Save time on installation with the tool-free, snap-on design. This valve seat disc forms a tight seal that reduces the risk of running water in the tank.