The heart of a copier on which the image is formed. It consists of an aluminum core with multiple layers of light and charge sensitive material such as selenium, or an organic based material. It is also commonly called the "OPC Drum".

The OPC (organophotoconductor) drum is one of the most expensive components of a toner cartridge and drives the entire print process. The OPC drum consists of a nonconductive (organic) coating on a nonferrous (aluminum) substrate. An OPC drum is used in an abrasive environment in which its surface is worn down by toner, wiper blades, and paper dust.