This is a new in the package Piston Ring set (1 set for each piston) for the 1974 1975 1976 1977 twin cylinder Kawasaki KZ400 Z400.   This is a standard size (STD) ring set.  Correct for discontinued Kawasaki part # 13008-5028.. This has the 2 compression rings and the lower 3 pc  oil control ring for both pistons, everything to get your pistons/ engine running nicely again.   Get your old bike up and running again. We only sell the best! This is a top-quality aftermarket item shipped new in the package. Good stuff if you are riding or restoring.