Serrated edges for aggressive performance. For use with most screw types such as hex, Phillips, slotted, pozi-driv, torx, and square drive. Also works in wood screws, sheet metal screws, and mechanical screws from No. 6 to No. 14. Can be used in a variable speed drill with regular or quick-change chuck systems. 1 end of bit used for burnishing screw, other end of bit used for extraction. High-quality steel for longer life and reusable bit. Set includes 1 each of No. 2 bit and No. 3 bit.