The "Industar" is a Russian made enlarger lens. It comprises 4 elements in 3 groups analogous to the Zeiss Tessar. The Industar performs well and costs far less than its illustrious German-made counterpart. TechSpecs: f/3.5-50mm (the ideal focal length for printing full frame 35mm negatives), fully coated optics, 6-blade diaphragm with continuous stop down to f/11, M39 "Leica" thread. As shown, the 2-part short series lens barrel includes a l3mm extension tube which can also be used for other applications such as repro and macro. The lens comes complete with its front cap and original container.