Save water and stop a running toilet with the Fluidmaster 502 PerforMAX Water-Saving Flapper. The 502 flapper is the gold standard of flappers. One of the unique features of this flapper is the ability to adjust how much water is flushed. Simply turn the dial left for more water and right for less water flushed helping save water and improve flushes. The 502 PerforMAX Flapper is suitable for 1.28 to 3.5 plus gallon per flush toilets. Only Fluidmaster has toilet flappers with built-in Microban protection. Not just simply a coating, Microban is specially built into the construction of flappers to fight flapper breakdown and combat bacteria.