Toner cartridge delivers outstanding results page after page in your Lexmark T640, T640dn, T640dtn, T640n, T640tn, T642, T642dtn, T642n, T642tn, T644, T644dtn, T644n and T644tn. Superior Lexmark design means precision pairing between printer and cartridge for value, quality and environmental responsibility you can count on. Lexmark Return Program cartridges are patented print cartridges sold at a discount in exchange for the customer's agreement to the license requirement that the cartridges will be used only once and returned only to Lexmark for remanufacturing or recycling. Cartridge yields approximately 6,000 pages.