it is Contax rudiment. Zeiss Ikon produced the film with the back paper (similar to those for 127 or 120 films but with sprockets). One was able to load this film on the light. After closing the back one needed to set the frame counter to red dot, then press the release button and fix it but rotating counterclockwise. Afterwards the film was advanced until the counter showed "zero". The camera was ready to shoot. The early Kiev manuals contain similar explanation but I wonder if such kind of film was produced in the USSR.