Toner cartridge uses a dry-type electro-photographic process. For use with Lexmark 4037, WinWriter 400. Print on copier paper, laser paper, transparencies, envelopes and standard office paper, recycled or not. A toner saver mode, which does not affect the speed of the printer, will reduce toner usage by up to 60 percent. The imaging process used in the print engine is LED (Light Emitting Diode) technology. The printing mechanism consists of 300 LED"s per inch of typical writing lines 8". This technology lends itself to better reliability, less mechanical wear, lower component and assembly costs and requires no moving parts. Help reduce resource consumption and waste by using the Lexmark Cartridge Collection Program. Designed for use with the IBM 4037 5E and 55E Laser Printers, Lexmark ValueWriter 300 and 600 and the WinWriter 400. Yields 3,500 pages.