Neiko 10052A Spot Weld Drill Bits, High Speed Cobalt Steel with Titanium Coating | 8mm (5/16-Inch) Special grade high speed steel cobalt mix is designed for long service life to withstand quick speed running rate Heat resistant titanium coating withstands high-performance metal and wood drilling when used in high temperature environments Flat ground surface on bottom half of bit provides additional strength and chuck hold on any welding drill Precise nibbed pilot tip design increases accuracy and prevents slipping when held down for marking purposes Standard 8mm bit at 1-3/4" (45mm) length is commonly used for locating spot welds in automobile frames