The ultimate Drill Bit Set! 115 sizes in High Speed Steel with Titanium Nitride (TiN) coatings ensures significantly cooler cutting temps. Bits will last 4 times longer than standard bits. Sizes: #1 - #60 with equivalent dimensional sizing clearly marked in thousandths of an inch, 29 fractional bits from 1/16 inch to 1/2 inch by 1/64 inch increments, and 26 letter bits, A - Z. For use on wood, metal, and plastic and more. Comes in a sturdy metal box with easy-access racks