These high-strength ARP bolts are great for installing most accessories. The 180,000 psi tensile strength bolts are made of 8740 chrome moly with a black oxide finish. All bolts are packaged in sets of 5 bolts with matching washers. These bolts have a 5/16-24 UNF thread pitch and 1 1/4" under-head length (total shank length including threads). The 3/8" 12-point head has a 5/8" diameter bearing surface.