External Hex, Internal Hex, Internal Torx, Hex, TX
Imperial, Metric, Torx, AF, SAE
4 mm, 5/16 ", 7/16 ", 9/32 ", 5/8 "
6.35, 25.4, 12.5, 19.05, 9.53
Special Steel, Molybdenum Steel, Alloy Steel, Steel, Chrome Molybdenum Alloy Steel
Gun-metal, Phosphatized, Oxidised, Black Phosphate, Black Oxide