Unknown micrometer

[Toolmaker51]

.......snipped........I read someplace that using a tool that was made for you or given to you by someone is to "shake their hand in friendship." I like that and find it to be so in a way.

Many relate to that. Family or friended tools, not surprising to sense a reaction to personal items, especially tools. Just reading his [clavius] post, I recall such occasions, though rarer, in property belonging to those you've no other connection at all.
Might be from era a person identifies with; though a boomer, somehow circa WWII tools and machines 'find' me.