This is a new in the package Piston Ring set (1 set for each piston) for the  1965 1966 1967 Honda CB450 Black Bomber.   These were the now famous twin cylinder, DOHC, four-stroke Hondas.  This is a standard size (STD) ring set that is correct for part #13011-283-000.  This has all compression and lower oil control rings 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.