[bridkarl]

Test equipment sort of. I picked this up today for $21. Apparently a Craftsman inside micrometer. Also a few random pieces marked USN - assume someone helped themselves in service.

How old? What would I use this for? I think it’s complete. I have various micrometer sets but not one of these tubular types.

[David]

Inside micrometer must have for rebuilding engines. You have more wear at the top of the cyl than the bottom. The navy stuff battle ships have guns up to 16 inch bore.