These screws are manufactured with alloy steel, which contains elements to help the screws become more responsive to heat and mechanical treatments. Material / Steel Material Grade/Class / B7 Finish / Black Oxide Thread Size / 3/8"-16 Thread Direction / Right Hand Fastener Length / 2 1/2 in Minimum Thread Length / 1 in Head Width / 9/16 in Head Height / 15/64 in Drive / Hex Tensile Strength / 125,000 psi Rockwell Hardness / HRC35 Dimensional Standards / ASME B18.2.1 Material Quality Standard / ASTM A193 System of Measurement / Inch Overall Length / 2 1/2 in Thread Style / Partially Threaded Type / Hex Head Cap Screw Head Style / Hex Thread Pitch / Partially Threaded Thread Type / Coarse