Stop your rocker arms from loosening forever with these ARP Perma-Loc rocker arm adjusters. Made from heat-treated, premium-grade 8740 chromoly steel, these adjusters provide 190,000 psi tensile strength for the utmost in reliability. Other features include exclusive heads with special shouldered stops to hold the adjusting wrench, precision CNC-machined threads to ensure optimum seat pressure, flush-machined set screws for proper contact on the studs, and, best of all, they don't require any special tools for installation.