Pro-BB – Forged piston in original OE form for big bore cylinderAll 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 lifeForged pistons are forged from 2618 aluminum for superior strength and durabilityBig Bore pistons increase engine’s displacement, torque, and peak horsepowerKits include piston, rings, wrist pin and circlipsReplacement two-stroke piston rings sold individually four stroke piston rings sold as a set