Malco, CB, cutter bit is impact driver compatible! These cutter bits feature a hex insert for ultimate flexibility for use on an impact driver or a drill. Cutter bits are long lasting, and feature a mill type cutting edge. The large flat allows for easy adjusting of the cutting edge location by sliding the bit up or down to extend bit life. The CB cutter bit fits both Malco Sheet Metal Hole Cutters, HC1 cutting 2" to 12" diameter circles and HC2, 2" to 24". The cutter bit can be easily replaced allowing the Hole Cutters to be used for years! Malco® Replacement Cutter Bit, For Use With: Model HC1 and HC2 Hole Cutter