A coiled film strip (2) is wound on the spool (1) rotatably mounted in a cassette shell (3). The film can be moved out of the cassette shell by turning the spool in the unwinding direction. The spool has flanges whose surfaces point towards the coiled film. They are spaced from the film by a distance decreasing from the inner axle to the outer periphery, so that the outermost periphery of the film is clamped. Ridges going around near the edges of the film on the inside of the cassette shell prevent the film from radially expanding.
