Oki Okidata image drums are unique in the printer world. These are not your typical developer unit or print cartridge like you see with other printer manufacturers.  Oki uses a two part developer system for their printers; one part is the toner cartridge and the other part is the image drum. Because of this two part system, the printer user saves considerable money on consumables because when the toner is out they only have to buy the toner, not the toner and image drum both. Many people do buy an extra toner when they replace their image drum to make sure that they have enough toner to fill the image drum. Some printer model's image drums come standard with a toner cartridge - see the product description to see if this is the case for your model printer. Image Drum Life The life of the image drum depends on several things, including the ambient temperature and humidity, the type of paper you use, and the number of pages per print job. Each time you start a new print job or turn the printer on or off, the drum has to rotate to start up and to wind down. Frequent one-page print jobs will age your drum more quickly than multiple-page print jobs. The image drum cartridge should normally last twice as long when printing mainly print job larger than 3 pages per job. This estimate is approximate since you normally will not print the same number of pages each time, plus the environmental conditions and paper type used may vary. When the image drum reaches 90% of its life, the CHANGE DRUM message will display in the control panel window or on your software window. You should have a new image drum cartridge and a new toner cartridge on hand at this point. Change the image drum cartridge when the print becomes faint or begins to deteriorate. Precautions for handling an image drum The image drum is fragile. To avoid damage to the new drum, take these precautions while handling the new image drum cartridge: Avoid touching the green drum surface. Be careful not to set the cartridge down on anything that might scratch the surface of the drum. Keep the drum from exposure to direct sunlight and don't let it sit in room light for more than 5 minutes. Leave it in the package until you are ready to install it in the printer.