Internal Hex, External Hex, Internal Torx, TX, Hex
Metric, AF, Imperial, Torx, SAE
3/4 ", 5.5 mm, 18 mm, 35 mm, 25 mm
38.1, 25.4, 6.35, 9.53, 19.05
Special Steel, Molybdenum Steel, Alloy Steel, Steel, Chrome Molybdenum Alloy Steel
Gun-metal, Phosphated, Oxidised, Black Phosphate, Black Oxide