THESE, SELF STARTING, MULTIPLE HOLE, STEP DRILLS ARE EXCELLENT FOR CUTTING NEW HOLES AS WELL AS REAMING OUT EXISTING ONES. THEY ARE GENERALLY USED TO CUT HOLES THAT ARE TOO LARGE FOR A STANDARD DRILL BIT. THEY ARE QUITE VERSATILE, AND ARE ABLE TO DRILL HOLES FROM 1/8" TO 1-3/8". THEY ARE GENERALLY USED IN ELECTRICAL CONSTRUCTION AND METAL FABRICATION. ONE BIT CAN DRILL BETWEEN 6 TO 13 DIFFERENT SIZE HOLES.