The 731BK cartridge is a high qualtiy black toner cartridge that has been produced by themselves. As a result you can expect minimum fuss and maximum compatibility when using the 731K laser toner cartridge in your printer. The toner powder in this 731 toner cartridge has been specially formulated to work with the i-SENSYS LBP-7100CN and all other compatible printers. No additional drum unit is required as the 6272B002 cartridge itself contains everything your printer needs to fuser the toner to paper.