Marketing InformationBest for older toilets, 3.5 gpf or more (before 1994). The Fluidmaster® 503 universal toilet flapper is designed to be a quick and effective replacement toilet flapper. With a flexible design, this flapper can be used on flush valves with or without mounting ears and fits most 2 in brass or plastic flush valves. Quickly replace old problem flappers with this universal design. The included kink-free metal chain eliminates flapper hang up, while the built-in Microban® extends flapper usage. Only Fluidmaster® has toilet flappers with built-in Microban® protection. Not just simply a coating, Microban® is specifically built-into the construction of our flappers to fight flapper breakdown and combat bacteria. The Fluidmaster® 503 2 in flapper, a flexible design for your toilet.