Only Fluidmaster has toilet flappers with built-in Microban® protection. The Microban® protection keeps the flapper cleaner by fighting flapper breakdown due to bacteria on the flapper itself. Fix a deteriorated flush valve seat without dealing with any messy glue or removing the tank with the 555C Flush Valve Repair Kit. It's easy to install the 555C, just peel the protective paper off the sealant ring then stick it right on top of an existing flush valve seat. The 555C includes the 502 Universal PerforMax® High Performance Flapper which is best for use in 1.28 - 3.5+ gallon per flush toilets. The 502 has a solid frame for ultimate reliability. Flappers with a solid frame do not twist and provide the best seal. Replace of fix your toilet flapper with a Fluidmaster toilet flapper. - See more at: http://www.fluidmaster.com/toilet-flush-valve-repair-kit.html#sthash.BhZfiQH3.dpuf