Gravity-tank flappers and seals cover the outlet where water leaves the tank to fill the bowl of a gravity-flush toilet. The flappers lift up to release water for flushing and reseat after flushing to hold water within the tank. The seals are rings that form a seal around the flappers. These parts are used to replace worn or warped flappers and seals that no longer seal properly and allow toilets to run continuously.