Billet 4340 Steel H Beam connecting rods. Closely monitored material mechanical properties for optimum performance. Designed and finish honed in the USA. Sizes held to some of the tightest tolerances in the industry, +/- .0001” and +/- 1 gram per end. Shot peened for improved fatigue life. Bronze wrist pin bushings. Exclusively using ARP 2000 fasteners.