Tool Steel .927 2.500 H-11 Alloy Steel Piston Wrist Pins The most over looked upgrade to a competition engine. Precision machined from solid H-11 bar stock, heat treated and triple tempered, and centerless ground to 0.0001” total tolerance. Inner diameters are honed on Sunnen equipment to precise size and finish requirements, while the outside diameter features a slight O.D. edge break to maintain maximum bearing area. These pins will give you the best strength to weight ratio available.