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.