Malco HC1 2-Inch-to-12-Inch Sheet Metal Hole Cutter Accessory for 1/4-Inch or Larger Drill Cuts 2"-12" (51-305 mm) holes in sheet metal including up to 20 gauge galvanized steel Commonly used by HVACR and Roofing Professionals Combination English/Metric diameter gauge High-speed bearings assure perfect cutting balance and a long cutting life Installs into the chuck of a standard electric drill as small as 1/4-inch Made in the USA