You simply cannot operate a colour laser printer without a functioning drum unit - like the Xerox 108R01121 - being installed. With a page yield that far exceed that of the corresponding Xerox toner cartridge, the 108R01121imaging drum unit kit works out incredibly economical and needs changinging rarely.Xerox estimate that this 108R01121 four colour imaging unit kit will need changing after 60,000 top quality prints. Xerox are so confident in the quality of the 108R01121 image drum unit multipack that they offer a full warranty directly.