This Chrysler Four Groove Steel Super Lock Features A 10 Degree Lock Angle And 3/8" Valve Stem Size. It Is Recommended For All Race Applications Because Super Locks Have A Wider Angle (10 Degree) That Better Distributes The Ever Increasing Valve Spring Loads Over The Retainer Than Typical 7 Degree Locks. Precision-Machined Out Of Super-Tough, Fatigue-Resistant Metal Alloy, Super Locks Fit Any Comp Cams 10 Degree Retainer.