You simply cannot operate a Xerox laser printer without a functioning drum unit - like the 101R00474 - being installed. With a page yield that far exceed that of the corresponding Xerox toner cartridge, the 101R00474 imaging drum unit works out incredibly economical and needs changinging rarely.Xerox estimate that this 101R00474 black image drum will need changing after 10,000 top quality prints. Xerox are so confident in the quality of the 101R00474 black image drum that they offer a full warranty directly.