Speed Pro Cast Piston .060 Over H581CP60 offers the performance / dependability of O.E. pistons.FeaturesHigh Quality AluminumControlled Casting Machining for improved reliability, and durabilityUp-tilt ring grooves improve piston to ring sealing provide greater blow-by controlFitsPerformance, Chevrolet, Big Block, 454 Based Engines (4.250 Bore x 4.000 Stroke)