They are four. They were born between 1929 and 1932. They are not easy to use : if you try to put a 120 rollfilm in it, you can't close the back ! Screen is dark; and, if you don't pay attention, you don't remember if you have taken the picture : you advance the film; or not... But these Original's are so lovely ! Number 1, the 611, the older with Tessar f4,5 taking lens, and number 2, the 612 (f3,8), have not a hinged back : some light may pass through... Number 3 (613, f,4,5) and number 4 (614, f3,8) have a hinged back. If you find one and like it, then you'll love TLR's !