Internal Hex, Internal Torx, External Hex, TX, Hex
Imperial, AF, Torx, Metric, SAE
5.5 mm, 11/16 ", 7/16 ", 5/8 ", 5/16 "
9.53, 25.4, 19.05, 38.1, 6.35
Special Steel, Molybdenum Steel, Alloy Steel, Steel, Chrome Molybdenum Alloy Steel
Gun-metal, Phosphatized, Oxidised, Black Phosphate, Black Oxide