Some toner cartridges require a drum to be installed, depending on the printer model and brand, which is usually very common for Brother laser printers. For these types of printers using separate drums, you need to take out both the toner cartridge and the drum, which are attached together, from the printer and then replace the cartridge in the drum. Please note that when replacing your cartridge, you do not necessarily need to replace your drum, only do so when your printer indicates it needs to be replaced.

To see how to replace these types of cartridges, we have the following video and pictures showing how to install the TN-450, similar to other cartridges such as TN-660: