You can buy these as individual cartridges or in multipacks to save on total costs.
Why 2 types of HP564 Black InkJet Cartridges? - HP Community
: Avoid touching the gold contact points or ink nozzles to prevent clogs or electrical errors.
: Third-party options like those from Hux on Amazon offer high-yield 564XL sets for significantly less, often around ~в‚№2,527.