All Two Wheel Werkz studs are made by ARP to our specifications. They use only SDF and CHQ standard 8740 chrome moly, which are both above aircraft standards. Each stud is precisely heat-treated to 200,000 psi. Following heat-treat each stud is centerlee ground to make sure it is as perfectly concentric as possible. ARP studs are thread rolled after heat treating, which gives them 1000% better fatigue strengh than studs that are threaded before heat-treat. Studs sold in sets of 10. Must be used with TWW-1019 CYLINDER HEAD NUTS.