Cordless knockout punches create round holes in sheet metal and other thin, flat materials. Their draw stud pulls a sharp-edged punch from one side of the sheet metal toward the die on the other side to cut a clean, accurate hole. Also called panel punches, they are commonly used to make openings for conduit and wiring in electrical boxes and panels. These cordless knockout tools drive through material more quickly and with less effort than manual knockout punches. They use brand-specific batteries, which fit different tools from the same manufacturer. Battery voltage and series must be compatible with the tool.