Wide range of inside diameter measurements possible by combining one or more interchangeable rods. Each interchangeable rod is marked with its measuring range. For models supplied with more than one interchangeable rod, the full measuring range is achieved by combining spacing collars with the rods. Both micrometer head and rods are satin chrome finished throughout. The sleeve is rotated to adjust the index line position when setting to a length standard. An inside-length standard is required for accurately setting the micrometer.