The TROY 02-81350-001 MICR Toner Secure Cartridge is a Magnetic Ink Character Recognition (MICR) toner cartridge designed for use with HP LaserJet 601, 602, and 603 series printers. MICR toners are specialized inks used in printing checks, ensuring compliance with banking standards, especially for the printing of magnetic characters at the bottom of checks, which are read by specialized check-processing equipment.