ARP 4001402 Stainless 300 12-Point Header Bolt Kit - Pack of 12 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 polished Stainless 300 steel, a proprietary alloy that is impervious to rust and corrosion Nuts are compact 12-point style, and premium-quality washers are included