Chevy Big Block, 3/8 diameter bolt, 3/8 wrench, 16 pack, 3/8 Size, 1.000 Under Head Length, Hex head, Stainless 300, ARP Header Bolts 400-1112ARP Chevy BB Header Bolts Header Studsaremanufactured ina variety of premium grade bolt and stud kits to facilitate installation of exhaust headers including the popular stainless stud kit with 12-point nuts.ARP Chevy BB Header Bolts Header Studs that areStainless 300 material arenot affected by corrosion or extreme heat, makingit ideal for the application. Whats more, the compact 12-point nut lets you easily slip a socket close to the pipe!Each ARP accessory stud or bolt kit includes the specific number of parts for your application, plus premium-quality washers and hex or 12-point nuts, as required. Studs are manufactured with a unique nut-starter nose that helps prevent cross-threading.ARP Chevy BB Header Bolts Header Studscome either black oxide chrome moly or Stainless 300. Both are nominally rated at 170,000 psi tensile strength; substantially stronger than Grade 8 hardware. Specially drilled NASCAR models are available for those who wish to safety wire their header bolts to Special NASCAR model prevent loosening.Studs are measured OAL (Over All Length) and Bolts are measured UHL (Under Head Length)