Pipe dial gages have a spherical anvil (ø.14") and a flat upper contact designed for measuring the thickness of a tubular wall. It can also be used by musicians to measure the graduated thickness of double reeds for oboes and bassoons. The anvil can be inserted into the tube for a distance of .78"
With the anvils closed, as shown in the photo, set the dial to zero by rotating it, if necessary.
The lifting lever at the top is depressed with the thumb and the anvil is raised. The lower anvil is then inserted into the tube, the upper anvil is allowed to close down on the outside of the tube and a direct measurement is taken by reading the dial.
It is possible to convert this gage for left hand use. The indicator can be swung around 180° and the lifting lever can be moved to the other side. You can also replace the indicator if it ever gets damaged. You will want to order Mitutoyo indicator 2414S.
For more information on thickness measurement in general, please refer to page 12 among others.