Speed Feed self-feeding wood bits are made for drilling fast holes in clean wood. The double wing spurs cut clean holesfor feeding wire or bolts through, and the feed screw and dual cutting edges provide up to 10 times faster drilling versus flat boring bits. Flutes are coated for fast chip removal. 1/4" power groove shank fits all 1/4" extensions. Set includes 1 each 1/2", 5/8", 3/4", and 1" Speed Feed wood bits.