Piston Kit (Cast Flat Head)Cast piston with flat headAll pistons are heat treated with a T-5 hardening and tempering cycleAll piston skirts are coated with a high-tech Molybdenum Disulphite coating for faster break-in time and increased piston lifeCast piston kits are gravity-cast aluminum alloy (not forged) with 18% silicone content, which produces an extremely light but very strong pistonAll rings are OEM replacementsReplacement two-stroke piston rings sold individually; four stroke piston rings sold as a set