This is a compatible HP Q6511A - Black MICR Toner Cartridge (6000 Yield). MICR is an acronym for Magnetic Ink Character Recognition. MICR Cartridges are used for printing checks. Banks read magnetic ink differently than standard ink, which allows them to reliably process checks. Magnetic Ink Recognition Toner; Regular toner mixed with IRON OXIDE particles, recognized by scanning devises. Mainly used for Check printing and bar coding. Built with NEW drums and NEW components that match all ABA standards (American Bankers Association). This HP Q6511A MICR Toner Cartridge is a Black toner used in MICR check printing. For use in HP LaserJet 2400, 2420, 2420d, 2420dn, 2420n, 2430, 2430dtn, 2430n, 2430tn, HP Printer/Scanner/Copier 2410, Troy 2420, 2430 MICR printers. Compatible with MICR Cartridges: Q6511A, Q6511X, THN-11A, THN-11X, 02-81133-001, 02-81134-001.