Making sure that your W850 series printer provides the results that you want requires more than just ensuring that you are using the right cartridges. Laser printers feature a complex and delicate printing system and if one component isn't working properly, you can be certain that results will suffer. Lexmark Photoconductor Units are essential for providing the best level of definition in your prints, ensuring that the toner is properly applied to the page. This pack contains a black photoconductor units with a 60,000 page yield.