The portrait studio chain that I worked for c.1979 used these. This one seems to be missing its viewfinder. These were a modular design, and could be made to take several film sizes. We used 70mm; can't quite tell what this one is- might be 46mm. The box on top would hold a slip of paper with the sitter's name and sitting number- this would be exposed at the edge of the image for ID purposes.
A real industrial artifact!