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 your engine block. The studs are manufactured in their own factory using the best processes, designs, materials, and engineering. Every main stud kit exceeds the most stringent aerospace specifications, and come complete with hardened parallel-ground washers and aerospace quality nuts. The studs are manufactured from 8740 chrome moly steel, and heat-treated to 200,000 psi tensile strength. J-form threads are rolled after heat-treat to create a fastener that has threads 1000% stronger than others. Be aware that, although ARP produces both studs and bolts, they recommend the use of main studs over bolts whenever possible for several key reasons. First is the ability to obtain more accurate torque readings because studs don't "twist" into the block. All clamping forces are on one axis. By the same token, there is less force exerted on the block threads, which contributes to improved block life (which is very critical on aluminum blocks). They also allow for easier engine assembly and proper alignment of caps every time.