These ARP main studs are made from 8740 chromemoly steel and have a 190,000 psi tensile-strength rating. They are precision centerless-ground and thread-rolled to Mil-S-8879 specs, with a black oxide finish for corrosion resistance. The kits come complete with hardened washers and high-strength hex nuts. They are perfect for helping to keep your main girdle in place and reduce bearing fatigue or distortion. After install have line bore checked or trued by a machine shop.