ARP Pro Rocker Arm Stud provides positive seating and is designed for use with Perma-Loc adjuster. It is constructed from 8470 chrome moly steel and is heat-treated to 200,000 psi tensile strength. This rocker arm stud features an extra-large radius base which makes the stud more resistant to flex. It is concentric within .005 T.I.R. thread pitch to thread pitch which gives more consistent rocker geometry.