The BU100505K is the Universal Upper Supply for all Sloan Flushmate Systems. Fits tanks 500, 501, 501A, 501B, 503, 504, F31A, F3A, F3AR, F3C, F3CR, F3CC, FCE, F3ER, F31, F3G, F3G2, F3L, F3LR, F3, F3R, F3M, F3MP, F3MR, F3O, F3U, F3UR, F3Z, F32, F3K, F3KR, F3G4, F3G3, F3GR, F3K1, F3K2, F4A, F4AP, F4P, F4L, F4LR, F4N, F4B, F4C, F4K, F4KR, F4MP, F4J, F4M, F4V1, F4V2, F4V, Fits all American Standard, Briggs, Caroma, Ceralux, Eljer, Gerber, HCG Hocheng Corp, Kohler, Lamosa, Mancesa, Mansfield, Niagara, Orion, Peerless, St. Thomas, Vitra, Vitromex, Vortens, Western Pottery, Xinqi