This multipack includes HP 950 and 951 original ink cartridges in Black, Cyan, Magenta, and Yellow. It is a pack of 4 cartridges with a total ink volume of 48.5 ml. These cartridges are compatible with HP OfficeJet Pro printers such as the 8100, 8600, 8610, 251dw, and 276dw. The black ink cartridge provides up to 1000 pages, while the color cartridges yield up to 700 pages each. HP's Instant Ink service offers a way to save on ink by automatically ordering replacements and charging based on pages printed, not ink used.