Genuine OEM HP DesignJet T1600 36In. Ink and Supplies
The DesignJet T1600 uses HP 730 ink cartridges and a separate B3P06A printhead. The printhead is the part that puts ink on paper; it's not another ink cartridge. Make that distinction first so an ink top-up doesn't turn into an unnecessary printhead purchase.
Toner Buzz carries genuine HP 730 inks in two sizes for each of the six colors, plus the B3P06A printhead. Pick the smaller or larger cartridge for the color you need. Matte black and photo black have different slots, so neither is a size alternative to the other.