Piston Kit - 94.94 mm - Yamaha WR/YZ450F 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, Piston kit includes piston, rings, wrist pin and circlips