Dials to adjust volume for a custom flush. Easy-to-adjust after installation; simply rotate flapper to desired volume. Chemical-resistant flapper won't rot, even in harsh water. Fits most toilets, even 1.6 gallon. Snaps onto existing mounting ears, or use adapter ring on 1" overflow pipe. Easy-to-install. Saves water. Now made with built-in Microban. Microban reduces the breakdown of the flapper caused by bacteria.