ARP 6221250 5-Pack Of Stainless Steel Hex Bolts, Size 5/16-18, 1.250 Under Head Length Bolts have a diameter of 5/16", a standard thread pitch of 18, an under head length of 1.250, and the wrenching is 3/8 Rated at 170,000 PSI, which is considerably stronger than Grade 8 hardware Manufactured from polished Stainless 300 steel, a proprietary alloy that is impervious to rust and corrosion Heads are traditional hex style Packaged on convenient 5-pack card