Features and Benefits: This is our most popular spot weld drill bit; 8.0mm or 5/16th is the most common size of spot welds that need to be removed; The Titanium coating on this bit will help prevent the bit from dulling due to overheating; The twist is the same size as the shank which is also 8.0mm and has a flat spot on it to be tightened into our DF-15 Series Spot Weld Drills; Specifically designed for the abuse of spot weld drilling; Flat ground for strength, centering nib to prevent walking; This Cobalt high-speed steel mix bit is 45mm long and works with all brands of spot-weld drills. Titanium (gold color) is a heat resistant coating that extends drill life by about 50%.