This is a complete OEM Quality Piston Kit – standard size for the Z50R 82-87 models. Comes with the wrist pin, rings, and circlips.  Honda has discontinued their piston and charges about $28.00 just for the ring set, pin, and circlips which makes our kit an easy choice.  We also recommend getting the top end gasket kit (part # TBW1175) or complete gasket kit (part # TBW1176) with this piston kit.