ARP head stud kits are available with your choice of conventional hex nuts or compact 12-point nuts. Premium quality parallel ground washers are also included with each kit. Clearly, they are the best on the market today, and the favorite of leading professional engine builders in all forms of racing. “On the basis of superior material, a special heat-treating process,and advanced manufacturing technology, ARP Pro Series head studs are clearly the very finest on the market today!”