Distinctive gold Bits, Bearings and Pivot Pin signify the longest lasting, fastest cutting, easiest adjusting solution for cutting holes in sheet metal. Hole Cutters quickly install into the chuck of any corded or cordless drill as small as 1/4" ( mm). Lightweight aluminum frames make these accessories extremely portable for a variety of hole cutting applications in sheet metal including 22-gauge (.759 mm) galvanized steel. A compact model HC1 Hole Cutter is adjustable for making 2 to 12" (51 to 305 mm) diameter holes. The larger model cuts 2 to 20" (51 to 508 mm) holes. A combination English/Metric diameter gauge is included on the adjustable pivot slide for both models and both models use the same mill-type Cutter Bit and parts. From the Manufacturer Sheet Metal Hole Cutter, adjusts for cutting 2-Inch to 20-Inch holes in galvanized sheet metal