Abstract: A device for transporting a plurality of slide film mounts in either direction between a pair of magazines in a slide film projector comprises a pair of endless mount-driving belts, each of which has a stretch adapted to run across the open end of each magazine in close contact therewith and at least a pair of spaced mount-catching stepped shoulder portions formed in the belt surface facing the open ends of the magazines. In operation from a starting position, each belt is driven by actuating a starting button so that a mount, if engaged by a shoulder portion, is received in one of the magazines by the movement of that shoulder portion of the belt, and, thereafter, one of the mounts housed in the other magazine is caught by that shoulder portion of the belt and moved out of that other magazine toward the film projection gate, stopped, and held thereat for projection so as to complete a cycle. Continuous operation may be effected manually or automatically by a control circuit.