The Fluidmaster 504 Long-Lasting Toilet Flapper is designed to last in any water conditions. Featuring chlorine-resistant material construction and built-in Microban to extend lifespan. Only Fluidmaster has toilet flappers with built-in Microban protection. Not just simply a coating, Microban is specially built into the construction of our flappers to fight flapper breakdown and combat bacteria. Quick and easy to install this versatile flexible frame design fits flush valves with or without mounting ears, and works with most 2′ brass and plastic flush valves. Best for use in older 3.5 GPF more more toilets. Quickly eliminate water waste and upgrade your old flapper with Fluidmaster’s 504 Universal Chlorine-Resistant long-Lasting Toilet Flapper.