Zebra 800077-740 YMCKO ribbons consist of yellow (Y), magenta (M) and cyan (C) panels for printing a full spectrum of colors by combining the colors using varying degrees of heat. The K panel is a black resin panel, typically used for printing text and barcodes and the O panel is a thin, clear protective overlay. Zebra 800077-740 YMCKO ribbons are used for printing a combination of full-color images and one-color text or barcodes.