Poly Sure Lock Rocker Arm Nut Set7/16 Stud Girdle Procomp Electronics rocker arm adjusting nuts are high-quality polylocks designed for full roller rocker arms. Made from heat-treated, premium-grade 4140 chromoly steel, these adjusters provide 190,000 psi tensile strength for the utmost in reliability. 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. They're available in various sizes to suit your needs.