Sealed Power Digital Diamond Profiled Pistons are perfect for engine builders looking for ways to build a cleaner-burning, longer-lasting vintage Chevy SB engine. This advanced piston technology lets rebuilders equip this popular engine with the ultimate in modern piston materials and engineering while still keeping that classic engine classic. Sealed PowerDDP Pistons feature:DDP Technology: Digital actuated diamond turning process produces precision skirt profiles. Barrel profile: Creates an oil wedge between the skirt and cylinder wall. Thermal Arching Compensation (TAC) Ring Groove Geometry: Machined uptilt offsets thermal arching distortion; squares the ring face to the cylinder. Next generation DUROSHIELD coating: Reduces friction and wear. Precision-machined pin bores: Accommodatespressed or floatingwrist pin installation. Can be used as full floating assembly. You must purchase 16 of LR63 lock rings. This listing is for 4.020, but we have others too.