1/2 represents 12.5mm and 3/8 represents 9.5mm. The 1/2 gauge sleeve is suitable for larger nuts with greater torque, while the 3/8 gauge sleeve is suitable for smaller nuts. ‌

S2 tool steel is an alloy of carbon (C), silicon (Si), manganese (Mn), chromium (Cr), molybdenum (Mo), vanadium (V), with ‌ excellent impact resistance, strength and toughness