Premium Compatible Jumbo 64015HA High Yield Black Toner Cartridge fully compatible with the Lexmark T640, T640DN, T640DTN, T640N, T640TN, T642, T642DN, T642DTN, T642N, T642TN, T644, T644DN, T644DTN, T644N, T644TN. The use of compatible supplies does not void your printer warranty.