Features and Benefits: Blair "11,000-SERIES ROTABROACH CUTTERS... for heavy duty use in sheet metal & materials up to 1/2" thick. Annular tools that cut clean, burr-free, and round holes fast... unlike twist drills that push or hole saws that tear through materials. Because they're hollow, there's no dead zone as with a twist drill, so less thrust is required and no deforming of stock or jagged edges occurs. Multiple cutting teeth, precision ground instead of stamped like hole saws, give long tool life.