BE ASSURED: We have been in the auto glass industry for 30 years. Our products are specifically designed for those who wish to do high-quality windshield rock chip repairs EXTRAORDINARY BITS: You will find amazing results with our Tungsten windshield repair drill bits. In our testing with just one drill bit, we drilled over 30 holes to the lamination of our practice glass. Slow speed recommended to avoid overheating. Results may vary. MEDIUM DIAMETER: Our Tungsten windshield repair drill bits are tapered with a medium diameter. This creates an excellent avenue for resin flow. The tip is .038" The full diameter is .045" The drill bit fits 1/16th inch sized collets. FAST: Our windshield repair drill bits are sharp so that even at a slower speed you can penetrate the glass quickly! COLLET INCLUDED: We have included the required 1/16th inch or 1.5mm collet that not only fits the American windshield repair drill bits but many others as well Windshield Repair Drill Bit Set of 10 by American Windshield Repair Systems. 1/6th inch Collet included