It's a toner cartridge. It's easy to change. It works in the printer well. It costs too much. Gotta' have it for the printer to work. The old one is easy to ship back.
Despite the cost, these are some of the best toner cartridges I’ve had in a laser printer. They continue to produce long after the printer shows them as needing replacing. I’ve stretched a black cartridge on “low” over a year until it finally started printing faintly. The color quality is very high with these as well. I recommend these cartridges.