Genuine OEM HP PhotoSmart 7150 Ink and Supplies
The PhotoSmart 7150's HP 56 black and HP 57 tri-color twin packs each contain two identical cartridges. They give you a spare of the ink you choose, rather than combining black and color in one pack.
Toner Buzz carries genuine HP 56 black, HP 57 tri-color and HP 58 photo ink as singles, plus the black and tri-color twins. Choose a single for the ink you're using up, or its matching twin when you'd like an extra cartridge of that same type.