External Hex, Internal Hex, Internal Torx, Hex, TX
Metric, Torx, AF, Imperial, SAE
9/16 ", 5.5 mm, 1/4 ", 5/16 ", 10 mm
6.35, 25.4, 38.1, 19.05, 9.53
Special Steel, Molybdenum Steel, Alloy Steel, Steel, Chrome Molybdenum Alloy Steel
Gun-metal, Phosphatized, Oxidised, Black Phosphate, Black Oxide