Laser printers and copiers not only need toner (ink powder) for printing, but also a drum (comparable with the print head of an inkjet printer). The drum puts the toner in the right place, and afterwards the paper is heated so the toner melts and is attached permanently to the paper. Drums, like all components of a printer, wear and will have to be replaced at some time, although they are fairly durable.
The OPC Belt Cartridge will print apploximately 60,000 images when printing on A4/Letter sized paper. When you see the REPLACE OPC BELT message on the LCD panel, you must replace the OPC Belt cartridge.