Plug and pin gauges are used to compare hole and slot dimensions or locations to specific tolerances. There are several basic types of products. Go gauges and no-go gauges are fixed limit gauges with gauging limits based on the plus or minus tolerances of inspected parts.  Go gauge dimensions are based on the minimum inside diameter (ID) tolerance of the inspected part. No-go gauge dimensions are based on the minimum outside diameter (OD) tolerance of the inspected part. Double-ended go/no-go gauges include a go gauge pin on one end of a handle and a no-go gauge pin on the opposite end. Progressive or step go/no-go gauges have stepped pins with the go gauge surface and the no-go gauge surface on the same side of the handle. Master gauge blocks, master or setting discs, and setting rings are master gauges used to calibrate or set working plug or pin gauges. Working devices are used for dimensional inspection and checked periodically against a master gauge. Annular plug gauges are large, usually over 8” in diameter, and used to set or check micrometer or other OD gauges. Some plug and pin gauges have internal or external threads for gauging threads parts or part features. Others are packaged in a kit with adjustment tools such as alternate extensions and contact tips, holders, and bases.