12x18 mat board with four 4x6 openings, perfect for showcasing multiple photos or paper artworks in a large frame. A mat board (passe-partout) is a cardboard sheet, usually with an opening in the center, that creates space between the photo and the frame. It protects your artworks by preventing direct contact with the glass while providing an elegant and professional presentation. This mat board is suitable only for paper-based works such as photographs, drawings, or prints, and should not be used with canvases.