I have a Fowler dial bore mic that uses split mandrels (?) to measure small bores. I originally bought it circa 1983 to measure chokes in shotgun barrels. I have noticed Fowler tooling in several tool catalogs, but nothing like the tool I own. I wish to buy another mandrel to measure a different size bore, but need help in finding the company. Feel free to email me directly at firstname.lastname@example.org.