Replacement for Lexmark 64004HA / 64035HA - Compatible Black MICR Toner Cartridge (21000 Yield) for Lexmark T640, T642, T644 . 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 MICR Lexmark T640, T642, T644 High Yield Print Cartridge, 64015HA MICR 21,000 Page Yield also replaces the 64035HA MICR which is a lower yield version than this cartridge.