Black 13"x19" or 11"x17" engineered wood with plexiglass, OR 8"x12" thin-frame (plastic) plexiglass - perfect for the infinity double-iris piece. Your choice of paper. 13"x19" may be matted to 11"x17", 11"x17" may be matted to 8"x12" and 8"x12" may be matted to 5.5"x7.5".