Tubular Inside Micrometer, Hardened Face

The 137 series models provide an accurate and flexible solution for measuring inside diameters when the available measuring range varies. The extension rod measuring system allows the same micrometer for a wide range of internal diameters without the need for separate instruments. The model is practical for machine shops, measuring laboratories, and workshops.
Features:
- Measuring range: 2-40" (includes both drum and extension arm combinations)
- Extension arms: 8 extension arms included in the package
- Measuring surfaces: hardened steel, offering good wear resistance for typical measuring applications
- Scale: 0.001" analog reading
- Measurement type: 2-point inside diameter measurement for holes, bushings, tubes, and cylinders.