The Mansfield genuine 228 flush valve is designed for Mansfied tank models, 3120, 3121, 3122, 3125, 3173, 3174, and 3165. This flush valve has a pretty unique design. The base of the valve is 2 inches, but it has a 3 inch openeing at the top of the flush valve. The 228 flush valve comes complete with the flapper, chain, flush valve gasket, and flush valve nut.