Fargo 84921 YMCK 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. Fargo 84921 YMCK ribbons are used for printing a combination of full-color images and one-color text or barcodes. The Fargo 84921 ribbon is specially-formulated to help your printer function properly. Fargo 84921 ribbon must be used in conjunction with Fargo HDP film for your specific printer model. The new ribbons have a modernized dye formula specifically made to provide the brilliant quality the printer is known for. HDP6600 printers should be updated to the latest firmware in order to produce the best print quality.