Toner Refill Store's premium compatible Lexmark black toner cartridges contain brand new parts and are 100% guaranteed to meet or exceed your expectations and surpass the print quality of the OEM (Original Equipment Manufacturer) Lexmark T640n. Our Lexmark T640n monochrome toner cartridges are made from the highest quality materials and are manufactured in an ISO-9001 certified factory. We also carry numerous toner refill kits which allow you to go green and SAVE! Toner Refill Store supplies each cartridge with a brand new smart chip which will get rid of your 'low toner' message. We also supply premium compatible drum units and Do-It-Yourself drum kits for select printers. The use of our premium compatible laser toner cartridges for the Lexmark T640n does not void your printer's warranty. Our Lexmark T640n521