Both black ink options listed for the HP DesignJet 750 C are named HP 45. C6650FN and 51645A are the different product codes, with no capacity distinction stated between them.
Toner Buzz carries genuine HP 45 black ink listed for this model. Use the full product code to distinguish the two cartridge listings.
Guaranteed fit for HP DesignJet 750 C
The products below are genuine OEM HP Supplies made for the HP DesignJet 750 C.