The HP DeskJet 3820 uses two compatible ink cartridges: black HP 15 (C6615DN), rated at about 840 pages, and tri-color HP 78 (C6578AN), rated at about 710 pages. Both are standard capacity. The same ink also works with the DeskJet 920C, DeskJet 940C, and OfficeJet 5110. Same-day shipping on most orders.
