This is a Soviet made 35 mm Finder for the classic rangefinders (Leica, Contax and their copies).Made of plastic with glass optics and metal mounting shoe.
This is an early, uncommon version with a metal front made by KMZ.
The finder is clean and fully functional – the image is clear and sharp. It was sold as a separate accessory for the Soviet 35 mm lens – Jupiter-12 (in both LTM and Contax bayonet mount).
I wish I could say more about this piece. It does not have brightlines (like the Leitz SBLOO finder), but the image is very clear and contrasty and you do not have to pay $400 or so for it. It is shown on a Zorki (Leica II copy.) Camera/lens are not included.