These printers use the C8550A cartridge:
Click On a Printer to View it's Cartridges
          HP Color LaserJet 9500
          HP Color LaserJet 9500 HDN
          HP Color LaserJet 9500 MFP
          HP Color LaserJet 9500 N
          HP LaserJet 9500
          HP LaserJet 9500 HDN
          HP LaserJet 9500 N