Model Name: INDUSTAR-50-2 ※M42 Mount Thank you for viewing. This is an Industar 50mm F3.5 lens with an M42 mount. I recently won this lens in a Mercari auction for 3100 yen, thinking it would be usable. The focus ring doesn't move at all, so I reluctantly removed the set screws, but that wasn't the cause, and it still doesn't move. The second image shows the removed focus ring. ※The three set screws are removed. There are two missing screws on the back (rear element). One was missing from the start, and when I put a screwdriver in the other, debris fell out. I gave up at this point, realizing it was beyond my abilities. The lens is small and difficult to assess for a novice. Please judge from the images. It is treated as a non-functional junk item. Thank you.