At “Rolls Royce” stereo devices... The body is made of cast aluminum, and the plate and cover are made of chrome-plated brass. The two Flor Berthiot 40mm F:3.5 lenses are fixed on a rectangular plate, itself screwed to the body of the camera. Between the two lenses, there are two dials, one of which allows you to select the speed and the other the aperture. On the body, a dial allows you to select Mono or Stereo modes, by placing a shutter in the right chamber and modifying the film advance. The armament is coupled to the advance of the film. The image format is 24 x 30 mm, allowing the views of two successive couples to be interspersed with a lens distance of 64 mm, which corresponds to the average eye distance. Focusing is up to 50 cm with a coupled rangefinder. There is a problem in Congress. Delivered from 1941 to 1957. Each device has a serial number engraved inside between the two image windows. The last three digits indicate the delivery date, the first two being the month, the third, to which must be added 1940 or 1950, giving the year... The remaining number in front being the serial number.