American Standard Flapper Assembly - 1.28 Gpf - AMS-7381043-402

This is a 1.28 gpf flapper, matched to American Standard high efficiency tanks that flush at 1.28 gallons. Putting it in a 1.6 gallon tank changes how long the flapper stays open, so the flush volume won't match what that toilet was engineered for. Match the flapper to the flush rating stamped on the toilet, not just to the tank opening it happens to seat on.

A running tank that refills on its own is almost always the flapper seal failing to hold against the flush valve seat, and on a 1.28 gpf American Standard toilet this assembly is the replacement piece. It's the cheapest repair to try before touching the fill valve, since a worn flapper leaks water past the seat continuously. If the tank keeps overfilling into the overflow tube instead, that's the fill valve, not this part.

Order it as American Standard 7381043-402.0070A. It ships as a complete flapper assembly rather than a loose rubber disc, so the seal and its chain attachment come together as one service part.

Only for the tanks that are actually rated 1.28 gpf and use this flush valve. American Standard has used several flapper and tower styles across its lines, so a building with a mix of vintages will need more than one part number on the shelf. The practical approach is to pull a lid on each model group, record the flush rating and the existing flapper part number, and stock to that list rather than assuming one flapper covers the whole property.

It's supplied unfinished. A flapper lives submerged inside the tank where nothing is visible once the lid is on, so there is no decorative finish option to pick. The only selection that matters is the flush rating and that it's the correct American Standard assembly for your flush valve.