With this camera Agfa introduced a new type of film cassette, though based on the earlier Ansco Memo design. The Karat cassette had no centre spool and therefore no moving parts, the film was wound from one cassette into another similar cassette and did not need to be re-wound. The film was moved by sprocket wheels which pushed the film into the receiving cassette. The Karat was easier to load than other 35 mm cameras making it ideal for those new to photography or who had previously used a roll-film camera.

The original model was supplemented by a model with an f3.5 Solinar lens and Compur or Compur Rapid shutter (1938) and one with an f4.5 Oppar lens and Pronto shutter (1938/1939), these both had chrome top plates. The f6.3 model was re-styled around 1939, the T setting lever was moved to the front of the camera, the strap lugs were removed, the shutter speed settings surrounded the lens and the lens panel was plain, the frame counter was completely visible, the black top plate was retained. A coupled rangefinder model with a Xenar lens was produced in small quantities during the war. The Karat was re-introduced after the war.

The Karat cassette formed the basis for the Iso-Rapid cassette introduced in the 1960s.

The rangefinder model was introduced in the early 1940s, this version with an accessory shoe was probably made in the late 1940s.