One of the more aggravating things found in many high performance engines is constantly having to re-adjust rocker arms. Until ARP introduced the patented Perma-Loc adjuster, there wasnt a poly lock on the market that you didnt have to continually tighten. There are several important reasons why ARPs exclusive Perma-Loc rocker arm adjusters wont loosen like others. First, the adjuster body is heat-treated all the way through (not just case hardened). This eliminates the thread movement common to others. Secondly, the threads are machined exactly perpendicular to the bottom of the adjuster, so it seats evenly and applies pressure on a full 360 circle. Lastly, the set screw is machined flush on the bottom (not pointed) so it will have optimum contact on the rocker arm stud.Youll find ARP Perma-Locs easy to use, too. The compact 12-point head is designed to hold your wrench in position while you lock the set screw with an Allen wrench. Features 12-point head with special shouldered stop t