ARP 6121000 Stainless Steel 5/16-18 12-Point Bolts - Pack of 5 Bolts have a diameter of 5/16", a standard thread pitch of 18, an under head length of 1.000, 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 compact 12-point style Packaged on convenient 5-pack card