Manufacturer Part Number: 40881|System of Measurement|InchThread Size (Inch)|5/16-18Thread Size (mm)|Drive Type|Hex SocketDrive Size|3/16Torx Drive Size|Drive Size (mm)|Length Under Head (mm)|Length Under Head (Inch)|1Head Type|ButtonHead Diameter (Inch)|Head Diameter (Decimal Inch)|Material|Alloy SteelFinish/Coating|Black OxideFull or Partial Threading|Thread Fit Class|3AMaterial Grade|Thread Standard|UNCFastener Standard|ANSI/ASME B18.3; ASTM F835Head Diameter (mm)|Head Height|Head Height (Decimal Inch)|0.1660inHardness|36-43 HRCThread Direction|Right HandAdditional Information|