External Hex, Internal Torx, Internal Hex, TX, Hex
Imperial, Metric, Torx, AF, SAE
5/16 ", 15 mm, 11/16 ", 25 mm, 33 mm
9.53, 19.05, 38.1, 6.35, 25.4
Special Steel, Molybdenum Steel, Alloy Steel, Steel, Chrome Molybdenum Alloy Steel
Gun-metal, Phosphatized, Oxidised, Black Phosphate, Black Oxide