Carl Zeiss Jena 20mm f/4.0 Flektogon lens with M42 mount in mint condition. The glass is clear, with no scratches, and free of dust or fungus inside. The focusing and stopping are smooth the aperture blades are clean, free from oil and the apertures are adjusting correctly, Optically the lens is in perfect condition. In original leather case with front and rear lens caps. Photos attached to the listing are part of this description.