ARP manufactures a variety of header bolt kits to facilitate the installation of your headers. Rated at 170,000 psi, theyre much stronger than stock and will last under even the most severe conditions. Each kit includes the specific number of parts required for the desired application, plus premium-quality washers and either hex or 12-point heads.Header Bolts, 12-Point Head, 20mm UHL, 3/8 in. Wrench, Steel, Black Oxide, Chevy, LS Engine, Set of 12ARP started applying technology to race fastener design and manufacturing in 1968. Todays critical diesel fasteners - head studs and bolts, main studs and bolts, and driveline - have been designed stronger than ever before to handle the extreme loads. As a results, installation pre-loads - the amount the fastener is stretched during installation - are very high.Specifications:Socket Size: 10mm 12ptUHL (Qty: 12): 0.984'Thread Size: M8'washers included