WW2 German map case

As far as I know, this is a German WW2 map case.
Complete made of brown leather and used to carry maps and other navigation items.
The case is missing its lid.
My friend bought this after an exhibition when a man came to him and told that he still had some WW2 items on the attic that he could have.
It does no longer fits his collection and there for he decided to part with it.

Markings: none that I could find
Condition: heavy used