Top End Piston Kit - CRF250R - 76.77 mm The piston is heat treated with a T-5 hardening and tempering cycle, The piston skirt is coated with a high-tech Molybdenum Disulphite coating for faster break-in time and increased piston life, Forged high compression piston improves power and torque across entire rpm range, Forged piston kit is forged from 2618 aluminum, Top end piston kit includes piston, rings, pins, circlips, top end gaskets, and cam chain