Two-stroke pistons are made from 4032 silicium Four-stroke pistons are made from 2618 silicium - the same material used to produce Formula 1 pistons Both include 3% copper in materials for better heat resistance All pistons are forged using a precision heat-treatment process that allows for production tolerances of just .005mm Forged piston tooling allows for the lightest available product Kit includes antiwear coated piston, rings, pin and circlips. PISTON KIT SX/XC65 44.96