Replace depleted toner in supported Lexmark MS4 printers with a black MICR toner cartridge compatible with the Lexmark 55B1000 supply format. MICR-TLN-551 is intended for document workflows that require magnetic-ink character recognition printing, including checks and other machine-readable financial documents. The cartridge is supplied as a new consumable and installs in place of the compatible toner cartridge. Match the printer model and its required toner reference before ordering, particularly where an MS4-series printer is deployed alongside similar Lexmark devices. The package contains the toner cartridge only; it does not add printer hardware or replace separate imaging components.