Knockout punches and dies create round holes in sheet metal and other thin, flat materials. They attach to a knockout driver's draw stud, which 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. Knockout punches and dies are commonly used to make openings for conduit and wiring in electrical boxes and panels. Kits include a manual driver, punches, dies, and other components. Sets include different-sized punches and dies that fit a compatible knockout punch driver. Individual punches and dies replace worn components or change to different sizes to make holes of a specific diameter. Draw studs fit knockout drivers of a compatible brand and power source (ratchet, manual-hydraulic, or cordless) to replace worn studs or allow drivers to use different punch and die sizes.