The ARP Main Bolt Kits are forged from premium 8740 chrome moly and all the bolts feature generous under-head radius and heat treating for utmost reliability. The threads are rolled after heat treating, which makes them about 1000% stronger than most other main bolts. These bolts are nominally rated at 190,000 psi, and are application-specific main bolts with reduced wrenching head and are designed for use in competition applications. Parallel-ground, hardened washers are included with each kit.