A Starrett Interchangeable-Anvil Outside Micrometer is a precision measuring tool that lets you cover a wider measurement range using one micrometer body and a set of removable (interchangeable) anvils/spacers. Instead of needing separate full-micrometer units for each 1-inch or 25 mm increment, you use a base micrometer and change the anvil to extend the measurement range. Starrett’s line includes mechanical and electronic versions, tubular bow-type frames, etc.
