This is an apochromatic 60mm f4.0 enlarging lens, most commonly used to make photographic prints with medium format 645 (6cm x 4.5cm) negatives. The 60mm focal length allows much shorter enlarger column heights or larger prints, compared with the 80mm focal length lenses often used for medium format enlarging. It is equipped with user conveniences such as a preset iris lever, illuminated aperture scale and click stop override. This model has 39mm LEICA mounting threads.