These printers use the C4127A cartridge:

HP LaserJet

HP LaserJet 4000

HP LaserJet 4000 N

HP LaserJet 4000 SE

HP LaserJet 4000 Series

HP LaserJet 4000 T

HP LaserJet 4000 TN

HP LaserJet 4050

HP LaserJet 4050 N

HP LaserJet 4050 SE

HP LaserJet 4050 Series

HP LaserJet 4050 T

HP LaserJet 4050 TN

HP LaserJet 4050 USB-MAC

Cycomm 3512 T

Cycomm 3522 T

TROY-Systems 617

TROY-Systems 617 T

TROY-Systems Troy 4000

TROY-Systems Troy 4000 EX

TROY-Systems Troy 4050

TROY-Systems Troy 4050 EX