Tap, drill, and screw checker gauges, also known as screw and wire checker gauges or screw and wire gauges, are sheets of steel with bored holes that correspond to standard drill, tap, or screw sizes. Each hole is marked with a nominal size. A bit or cutting tool is inserted into the reference gap of the checker to confirm the size. These gauges are commonly used in mechanic’s shops, maintenance and MRO applications, and for metalworking, production, fabrication, and woodworking applications.