Took up to twenty exposures of 2828 mm frames on paper-backed, singly perforated, 35 mm wide film pre-threaded into double-ended cartridge with film supply and take-up spools.
Because the wire was pulled past the head by the take-up spool, the actual wire speed slowly increased as the effective diameter of the take-up spool increased.
The cartridge has a captive take-up spool, but no supply spool: the film and backing paper are simply coiled tightly and placed in the supply end of the cartridge.
It enables a partially exposed film to be removed from the camera in daylight for processing provided the left-hand take-up spool was placed in a cassette.
