This is an MTI MICR Toner Cartridge for TROY MICR 601, 602, 603 and HP LaserJet M601, M602, M603 printers. It is custom built to replace HP CE390A and TROY 02-81350-001. HP LaserJet and Troy MICR printers only accept MICR cartridges that have been modified to TROY specifications. MTI © MICR cartridges are specially engineered to include the TROY modification. All our products are manufactured in ISO 9001 certified facilities and rigorously tested for quality assurance before shipping. We offer an exclusive 30-day customer satisfaction guarantee and 2-Year Manufacturer Warranty. Our dedicated customer care staff is available 9 a.m. to 7 p.m, Monday through Saturday, to answer any questions and provide technical support. Note: Using a compatible MICR cartridge will not void the printer warranty.