Abstract: A film cassette for containing and displaying an endless loop of film has a housing constructed of two symmetrical elements, an end of the housing being deeper to accommodate a larger portion of the film. Apertures are formed in opposing sides of the housing and extend the full width of each side or approximately twice the width of a frame of film. A dual film gate assembly is contained within the housing and has two back plates to support the film and two snap on front plates which define a film gate on either side through which a leader of film is threaded. Both the back plates and the front plates have openings which approximate the size of a frame of film to allow light to pass from one aperture to the other in a straight line path. A film advancing means consists generally of a shaft having two sprockets mounted thereon, each sprocket extending through an index slot in a film guide plate and having teeth or other structure to positively engage the film and advance it through the film slot.

Abstract: The disclosed structure is a collapsible integral three-panel flat mailing slide viewer including a removable adapter for viewing film strips. The viewer may be formed for 2-D or 3-D slides.