Evolis R5F008S14 YMCKO ribbons are used for printing a combination of full-color images and one-color text or barcodes. YMCKO ribbons consist of Y (yellow), M (magenta), C (cyan), K (black resin) and O (clear overlay) five panels. 1. Yellow (Y), magenta (M) and cyan (C) panels for printing a full spectrum of colors by combining the colors using varying degrees of heat. 2. The K panel is a black resin panel, typically used for printing text and barcodes. 3. The O panel is a thin, clear protective overlay that is applied over the entire surface of your cards.