ARP Custom Age 625+ Nissan RB26 Head StudsIncludes: 14x M12 Custom Age 625+ studs 14x Chrome Moly Steel 12 point nuts 14x hardened and parallel ground washers and a 1 2 oz. pack of ARP Ultra Torque fastener assembly lubricant. All ARP Custom Age 625+ studs are centerless ground, heat treated prior to thread rolling and machining, nominally rated at 270,000 psi tensile strength and are reusable as compared to OEM Torque to Yield (TTY) head bolts. Optimum design, enhanced reliability and