Internal Hex, Internal Torx, External Hex, Hex, TX
Imperial, Metric, AF, Torx, SAE
13/16 ", 7/8 ", 5.5 mm, 5/16 ", 5/8 "
1, 1-1/2, 2-1/2, 1/2, 3/8
38.1, 25.4, 19.05, 6.35, 9.53
Special Steel, Molybdenum Steel, Alloy Steel, Steel, Chrome Molybdenum Alloy Steel
Gun-metal, Phosphated, Oxidised, Black Phosphate, Black Oxide