The 3,5/10,5cm Industar 7 was officially mounted on medium format cameras: the Turist (1934-38), Reporter (1937-40) and the Fotokor 3(1939-40).
This version for LTM camera is the only to be known, for the moment. We don't know by whom it was made. The serial number is very early and denotes a prewar lens, but the conversion can have been made after.
Photos made with an A7 Sony, dates borrowed to the "Princelle".