For the following:

Epson AcuLaser C9100
Epson AcuLaser C9100BN
Epson AcuLaser C9100DPS
Epson AcuLaser C9100DT
Epson AcuLaser C9100PS
Regional compatibility: Worldwide

Your drum unit will shut down at every cycle of 30K printed pages, leaving you unable to print, even though there may be plenty of life left in the cartridge.
Slash printing costs by simply replacing the chips which shuts the unit down, to extend drum unit life.
Each chip lasts for one cycle of 30K printed pages, after which it must be replaced.

Some drum units are region specific. If there is a region code in the description, please make sure that it matches the region of your drum unit. If there is no region code, then the chips are not regional and will work anywhere in the world. If you are not sure, please check your drum unit model matches the one in the description, or send us a question.