Yes, the MIR (= Peace) is a simply Z4. These Zorki's ( = Sharp seeing) were going out in 1990/1991 for a few Deutsche Mark (DM) really a few €'s. The Zorki 4K was an export product with improved film level and fixed spool. But the Jupiter optics are really good. Till 1949 they were made of original Zeiss supplies taken away from the factory in Germany. If you have a good J-8 or J-12 they can almost compete with some Leica lenses.