A piece of ErEl headgear you don't see everyday...

[Albert]

... at least not as a purist pre-May 1945 collector. But since some of us are not as purist here it is:

[Albert]

Stamping reads "Robert Ljubshtejn Berlin" which is the Russian spelling of Robert Lubstein Berlin. The 56 is the size, so the 50 could be the year even though it is not followed by "г" which is the abbriviation for "year":

[Anders S]

Very fun to see, thank you for sharing but gee what a sad end for a once proud logo...