The Robot I was quite small, the body measuring 4¼ inches long, 2½ inches high, and 1¼ inches deep. A very sharp zone-focusing "f/"2.8, 3.25 cm Zeiss Tessar lens added 1/2 inch to the camera depth. It was about the size of the much later Olympus Stylus although it weighed about 20 ounces, approximately the weight of a modern SLR. The die-cast zinc and stamped stainless steel body was crammed with clockwork. A spring motor on the top plate provided the driving force for a rotary behind-the-lens shutter and a sprocket film drive. The film was loaded into cassettes in a darkroom or changing bag. The cassettes appear to be based on the Agfa Memo cassette design, the now-standard Kodak 35 mm cassette not yet being popular in Germany. In place of the velvet light trap on modern cassettes, the Robot cassette used spring pressure and felt pads to close the film passage. When the camera back was shut, the compression opened the passage and the film could travel freely from one cassette to another.