Strange Leitz lens. I don't know what it was used for. Looks good, no issues. Concave rear. Will come with mount ring that can act as simple focusing aide. Remark, this is a collectors item, not useful for photography purpose. 

*i had two samples, this is last one - i am using photos from previous listing, the lens is exactly like this with different serial number: 1982713 and brass is less obvious since the matte black protective paint still present (i can polish it off if required

EU buyers: You don't want to pay high US$ to EUR conversion fees, let me know and i will relist .de with price in EUR currency.