These printers use the 4421C001 cartridge:

Canon MAXIFY GX-3020

Canon MAXIFY GX-4020

Canon MAXIFY GX-5020

Canon MAXIFY GX-5520 X

Canon MAXIFY GX-5550

Canon MAXIFY GX-6021

Canon MAXIFY GX-6040

Canon MAXIFY GX-7020 X

Canon MAXIFY GX-7021

Canon MAXIFY GX-7040