The HP No. 81 Dye Ink Cartridges are part of a modular ink system that delivers fast printing automatically. Experience the widest color gamut and smoothest color transitions offered by HP large-format printers with HP No. 81 Dye six-color ink system and newly formulated dye-based inks. HP No. 81 ink supplies are HP engineered and tested to work precisely with HP printers to deliver the professional results you expect.