This is a Synchro-Compur shutter mounted behind the lens, which is interchangeable. The shutter speeds go from "B" to 1/500. The 35mm Skoparex is unusual, but not hard to find. The 135mm f/4 Super-Dynarex is relatively common, although the 200mm and 350mm Super-Dynarex lenses are relatively rare and expensive.
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