ARP 2000 RB25 Head StudsThese head stud kits feature premium grade ARP 2000 material ( Not 8740 material as all previous kits ) that is rated at 220000 psi tensile strength. They are heat treated prior to thread rolling and machining and are rated at a whopping 220000 psi. The pro series kits are also available with 12 point nut, and all kits come complete with hardened parallel washers for an even load distribution and accurate torque readings.