Carl Zeiss Jena Flektogon 20mm f4. M42 mount. Comes with a valuable leather case, which is also in good condition. Similar to the 35mm lens I have listed separately, there are no noticeable scratches on the exterior. I believe this is also in the category of a beautiful item (this is just my personal opinion). The focus ring has a smooth feel with no issues. The aperture ring also functions without any problems. No oil stains are visible on the aperture blades. There may be some minor dust particles, but I don't see anything concerning, including mold. *For convenience, I have selected K-mount, but it is an M42 mount. I used it with Canon and Pentax cameras via an adapter. *This lens is suitable for personal use in my hobby (it's in good condition among my collection of old lenses). However, as it is decades old, it may not be suitable for those who are concerned about minor details. No claims and no returns. Focal length...19-70mm Maximum aperture...2.9-4 Other features...Old lens, with front lens cap, with rear lens cap