This is an adapter to convert Leica screw mount lenses to Canon EOS R mount. Leica screw mount is also known as L39 or M39. I received this mount adapter with an old lens I purchased for a film camera. However, I am not a Canon EOS R user, so I am putting it up for sale. The exterior has no noticeable scratches and is very clean, so I think it's safe to say it's like new. It feels well-made and should work without any problems. For Canon users, please consider purchasing it.