These printers use the Q5942A cartridge:
Click On a Printer to View it's Cartridges
          HP LaserJet 4240 N
          HP LaserJet 4250
          HP LaserJet 4250 DTN
          HP LaserJet 4250 DTNSL
          HP LaserJet 4250 N
          HP LaserJet 4250 TN
          HP LaserJet 4350
          HP LaserJet 4350 DTN
          HP LaserJet 4350 DTNSL
          HP LaserJet 4350 N
          HP LaserJet 4350 TN
          TROY-Systems Troy 4250
          TROY-Systems Troy 4250 /T
          TROY-Systems Troy 4250 /T SECURE
          TROY-Systems Troy 4250 /TSECURE EX
          TROY-Systems Troy 4350
          TROY-Systems Troy 4350 N/NT
          TROY-Systems Troy 4350 N/NTSECUEX
          TROY-Systems Troy 4350 N/NTSECURE