For temporary exhibitions or framing posters, the clear plastic clips provide a secure hanging mechanism with minimal visual obstruction. Use them with works of art on paper (either matted or with a thick backing board and glass) or on canvas board with glass. Uni-Frame 20 accommodates pictures from 10" to 20" either horizontally or vertically. Uni-Frame 40 handles work from 16" to 40" in either direction. Both accommodate up to a 5/16" thickness of material. Note: Foam Board and Plexiglas are not included with this framing system.