Flushmate M-101526-F31 FM III 503 Pressure Assist tank less Handle for most OEM 2 piece toilets using Flushmate For ALL OEMs except Kohler K 4404 tank and Gerber 28-385 tank ; CAUTION does NOT work in One-piece Fixtures ; Tank-to-Bowl Gasket It does NOT fit 10 Inch rough-in tanks, only 12 Inch rough-in tanks. Rough-in refers to the distance from the wall to the bolts at the center of the drain. ONLY used on model 503 Flushmate Systems 1.6 gpf tanks Does not include Cartridge