RockerArm Adjt Screw, Mag Polylocks 7/16" Rocker Stud, Magnum Polylock Set for 7/16" Rocker Stud, None, Tapered for extra strength in locking points, our Magnum polylocks are 1.300" tall with a .665" diameter for use with 7/16" stud rockers., Engine Rocker Arm Adjusting Nut.