External Hex, Internal Torx, Internal Hex, TX, Hex
Imperial, Metric, AF, Torx, SAE
7/8 ", 5.5 mm, 5/16 ", 23 mm, 11/16 "
3/4, 2-1/2, 1-1/2, 1/2, 1
19.05, 9.53, 25.4, 6.35, 12.5
Special Steel, Molybdenum Steel, Alloy Steel, Steel, Chrome Molybdenum Alloy Steel
Phosphatized, Gun-metal, Oxidised, Black Phosphate, Black Oxide