ARP 3008243 Perma-Loc Rocker Arm Adjuster - Pack of 16 Exclusive 12-point head, with special shouldered "stop" to hold the wrench, eliminates the need for special adjusting tools Forged in-house from grade A 8740 alloy chrome moly steel and heat-treated throughout for a 190,000 psi tensile strength, not simply case hardened like others are Threads are precision CNC-machined exactly perpendicular to the bottom of adjuster to ensure an optimum seat, even pressure, and maximum engagement Bottom is flush-ground perpendicular to the threads, so it seats evenly, and the set screw has flush-machined tip for optimum contact and seating on stud Designed for aluminum rockers, and features an overall length of 1.200, a thread size of 3/8 - 24, and a body diameter of .550; sixteen adjusters per package