There are many important reasons to use ARP Main Stud Kits, including the elimination of main cap walk and fretting, As well as protecting the threads in yourengine block. The studs are manufactured in our own factory using the best materials, processes, designs and engineering. Every ARP Main Stud Kit exceeds the moststringent aerospace specifications. All kits come complete with parallel-ground washers and aerospace quality nuts. Some applications have provisions for mounting windage trays and have specially designed standoff studs with serrated lock nuts to position the windage tray and lock it securely in place.The studs are manufactured from 8740 chrome moly steel, heat-treated in-house to 200,000 psi tensile strength, and precision J-form threads rolled after heat-treat to create a fastener that has threads 1000% stronger than others. Don't settle for anything less than the best. Insist on genuine ARP studs.