This is a Soviet made 85 mm Finder for the classic rangefinders (Leica, Contax and their copies). Made of plastic with glass optics, with metal shoe and metal front.
The finder is clean and fully functional – the image is clear and sharp. It was sold as a separate accessory for the Soviet 85 mm lens – Jupiter-9 (in both LTM and Contax bayonet mount).
It is shown on a Leica IIIa (camera and lens are not included)