Skunk2 Racing's Ultra Series X-Beam Connecting Rods are manufactured from Forged 4340 Chromoly Steel. All forgings are then fulley machined and subjected to a battery of processes that include heat treating, shot peening, and magnafluxing to insure the ultimate in strength! Finally each set is balanced to within +/- 1.5 grams. Our x-beam design greatly reduces weight while maintaining strength by removing material and strategically shaping the beam; resulting in a very high strength to weight ratio, making them great for circuit and drag racing. The ribs/straps on the pin end increase strength and stiffness under high engine loads and engine speeds. The step on the big-end (crank journal side) is designed for strength, rigidity, and to maintain roundness. These features along with the 3/8" ARP® 2000 hardware provide you with a top of the line connecting rod that can handle most anything you can throw at it. Not Compatible with OEM Pistons and May Require Notching for Clearance on 88mm and Smaller Bore