These are an essential item if you are restoring, riding or racing your now vintage Kawasaki KZ750 twin cylinder model motorcycle : This is a pair of 2 piston rings sets (...so enough for 1 engine).  These are STD. size. Correct replacement for part #13008-055.  There are for standard size Kawasaki pistons.  Perfect fitment. No disappointments here, we only sell the best!  These sure are fast, fun bikes!   These will fit all year of twin cylinder KZ750 models: 1976 (B1), 1977 ( B2) 1978 (B3)1979 (B4) and also the 1980 KZ750 G1 LTD, 1982 KZ750 M1 CSR Twin, 1983 KZ750 K1 LTD Belt,  and the 1984 KZ750 K2 (Canada only). Top quality aftermarket item.