ARP main stud kits help eliminate main cap walk/fretting and protect the threads in your engine block. They include studs made from 8740 chromoly steel and heat-treated in-house to 190,000 psi tensile-strength rating. The precision J-form threads are rolled after heat-treat for much stronger threads than the competition. Kits come complete with hardened parallel-ground washers and high-quality nuts. Kit includes M12 main studs and M8 side (cross main) bolts.