The Starrett 124BZ Mechanical Inside Micrometer Set is a high-quality tool designed for precise measurements inside cavities or hollows. With a range of 2-12 inches and the ability to use a 10 extension rod, this micrometer set is suitable for a variety of metalworking tasks. Made by the reputable brand Starrett in the United States, this micrometer features mechanical readings with a resolution of 0.00100 inches. Ideal for inspection and measurement in CNC, metalworking, and manufacturing industries, the Starrett 124BZ is a reliable and accurate tool for professionals.