Zorki Periscope Military camera intended for use in periscope use in hidden front watching. -See without be seen-. No finder nor rangefinder no synchro. Standasd body, self timer and 1 to 1/1000 sec + "B". 1977 production from 4K models destinated for reposition of old cameras in PDF military hand periscopes. There were previous Zorki Periscope built from standard model 4.
Further matter can be seen at: http://www.photohistory.ru/ArmyCam.html PDF of 1943 with FED camera and http://www.almanacwhf.ru/?no=5&art=8 (War, History and Events). Compare this Zorki Periscope locking mount with the war time FED Photosniper.