Genuine OEM Canon PIXMA MP540 Ink and Supplies
The Canon PIXMA MP540 has a PGI-220 black cartridge and a separate CLI-221 black cartridge. CLI-221 also supplies cyan, magenta, and yellow, so black ink should be selected by family code.
Toner Buzz carries genuine Canon inks from both families for the MP540. Individual cartridges handle a single ink need, and the CLI-221 pack combines its black and three color cartridges for a grouped change.