These products are guaranteed to work with your Lexmark T640dn printer.
Lexmark T640dn is a Workgroup monochrome laser printer and the maximum media size admits by this printer are 8.5 x 14 inch (Legal) and 8.25 x 11.7 inch (A4). The interface used by this printer is Ethernet 10/100 Base-TX, parallel and USB. The laser printer is supported with duplex printing and the speed of the duplex print (letter) is up to 30 spm. The maximum media capacity of the printer is 3850 pages. This laser printer includes one toner cartridge which delivers up to 6000 pages.