Fits LS1/LS2/LS3 Gen 3 and Gen 4 engines. These ARP Pro Series Head Bolts are made of 8740 (190,000 psi tensile strength) material and utilize a 12-point head. They are cold-forged and heat treated prior to thread rolling and machining ensures molecular integrity. Kits come complete with hardened washers. ARP fasteners are a must for performance applications!