I have four items - probably these are what you call 'film sheaths', 10x15 cm size. Each one is a black metal plate with a flexible frame of 5mm wide which is attached to the plate with one of its shortest side. A sheet of film is to be put on the plate under the frame, and the whole thing should then be inserted into a plate/film holder (which I don't have for this size). I don't have a digital camera, so photos cannot be provided. The items are located in Belarus (former Soviet Union).