Most of the printers come with pre-installed chips. These chips keep a check on the cartridge's toner level. When the toner depletes, the chip sends a message notifying you that the cartridge is running low on toner. Even after you refill the cartridge, the chip doesn't reset itself and maintains the same toner level as before. In order to get the printer to recognize the refilled toner, you have to reset the chip's ink level. At inkjetrefillkit.net, we carry for these toner printers: Brother, Canon, Dell, Epson, HP, Konica Minolta, Kyocera Mita, Okidata, Ricoh, samsung, Sharp and Xerox