These screens are used in cinemas, schools, lecture rooms, etc. They include projection screens for three-dimensional presentation; also portable screens, rolled in sheaths or contained in boxes, for mounting on tripods, on tables, or for hanging from the ceiling. They are often made of a fabric coated white, silver or with glass grains (microspheres), or of sheets of plastics; these fabrics or sheets are generally perforated. To fall in this heading, however, they must be clearly identifiable (e.g., by means of hems or rims, eyelet-holes