Genuine OEM HP DeskJet 870 Cse Ink and Supplies
The 870Cse's black ink comes in HP 45 cartridges, with a twin pack adding a spare of the same cartridge. That pack doesn't include color ink; the printer uses HP 41 for tri-color printing.
Toner Buzz carries genuine HP 45 black singles and twin packs, along with individual HP 41 cartridges. Choose the twin when you want black ink in reserve, or select the black and tri-color cartridges separately when you need both.