These printers use the C6625 cartridge:

HP DeskJet 816 C

HP DeskJet 825 C

HP DeskJet 825 CVR

HP DeskJet 840 C

HP DeskJet 841 C

HP DeskJet 842 C

HP DeskJet 843 C

HP DeskJet 843 CXE

HP DeskJet 845 C

HP DeskJet 845 CVR