Analog bore micrometer (internal micrometer), in this case from the brand MICRO, which also has an instruction manual in the box. It is used just like the previous, digital version, to measure internal diameters with very high accuracy.
Specifications and usage:
• This model appears to be for 65–70 mm in diameter, which is visible on the scale ring.
• It has three expanding measuring arms that automatically center in the hole when measuring.
• The reading is made on an analog micrometer scale (in millimeters with 0.01 mm resolution).
• The black part on the right in the box is probably a handle or an adjustment key.
• The milled space in the box is probably for extra measuring devices or setting rings that are missing from the picture.
Summary:
This is a very precise and sensitive tool used in the mechanical industry, workshop production and quality assurance, when you need to check, for example, the fit of shafts and holes.