Genuine HP C9504ee black ink cartridge (No339) TWIN PACK, 2 x 21ml for use in the DeskJet 5740, 5745, 5940, 6520, 6540, 6540d, 6620, 6840, 6940, 6950, 6980, 9800 & 9800d, OfficeJet 6310, 6315, 7210, 7310, 7410 & K7100, PhotoSmart 2575, 2610, 2710, 8050, 8150, 8450, 8450gp, 8750, 8750gp, D5160 & Pro B8350.