Fluidmaster®'s Universal Chlorine-Resistant Toilet Flapper is designed to be a longer lasting flapper replacement, that fits most 2” flush valves. Best for older toilets, 3.5 GPF or more (before 1994). Built tough to last in harsh water conditions, 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. Its solid frame ensures a secure seal, by resisting bending, or twisting during flushing. Replace your leaky, or faulty flapper fast, with Fluidmaster®’s 501C Solid Frame Universal Flapper.