"Hypereutectic. Piston made w/high strength alloy &silicon for excellent strength & scuff resistance. This advance combination allows tighter bore and improves sealing for less blow-by. Higher strength than cast, designed to retain standard ring gaps in top groove.. DUROSHIELD? skirt coated piston. Moly-graphite coating, Extends engine life; Reduces friction for higher fuel economy and prevents damage from inadequate lubrication on start-up; Eliminates scuffing and wear; Helps improve cylinder sealing for less blow-by. "