The Fluidmaster® 501 universal chlorine-resistant toilet flapper is designed to be a longer lasting and high-quality flapper replacement, to fit most 2 in flush valves. Built tough to last in any water condition, with chlorine-resistant materials and built-in Microban®. 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 solid frame ensures a secure seal, by resisting bending or twisting during flushing, so you never have to jiggle the toilet handle again.