Enhanced piston pin oiling slots, radial boss machining, and annular grooves for improved wrist pin lubrication Lightweight piston with a tight piston wall clearance for a quieter running engine Skirt coated for reduced friction and improved break in performance Ring land treatment for improved ring seal and oil control Double bridged forging design where noted Kit includes piston, rings, wrist pin and pin locks. PSTN KT YAM YZ450F STD B