ARP 1001412 Black Oxide Hex Stud Kit Premium grade stud kit to facilitate installation of exhaust headers Rated at 170,000 PSI, which is considerably stronger than Grade 8 hardware Studs are 3/8" in diameter and have a 1.670 overall length; 12 pieces Manufactured from black oxide finished chrome moly steel Nuts are traditional hex style, and premium-quality washers are included