ZEISS-IKON IKONTA 520/16 ( 1937 )
The square format Ikonta was the Ikonta B, 520/16. It was introduced a bit later than the rest, around 1937. It could be had with 75/3.5 Tessar in Compur Rapid shutter, or 75/3.5 and 75/4.5 Novar lenses, in either Compur or Klio shutters.
This camera is from Mr. KOKSAL's "Old Camera Collection"...