These printers use the Lexmark 63H5721 cartridge:

Lexmark 4040

Lexmark Optra N-240

Lexmark Optra N-245

Lexmark Optra N model 240

Lexmark Optra N model 245

Lexmark Optra N Pro

Lexmark Optra N Series

Dataproducts DDS 24

Dataproducts DDS 24 T

Dataproducts Digital Document Server 24

DEC LN 24

Digital-DEC LN 24

Hitachi Beamstar M-324

Hitachi PC PL-2600

HP 8000

HP LaserJet 5 SI

HP LaserJet 5 SI MOPIER

HP LaserJet 5 SI MX

HP LaserJet 5 SI NX

HP LaserJet 8000

HP LaserJet 8000 MFP

HP LaserJet 8000 DN

HP LaserJet 8000 N

HP LaserJet 8000 Series

HP Mopier 240

HP Mopier 240 Network MFP

HP Mopier 320 Network MFP

Interface-Systems 9324

Interface-Systems 9624

Konica Print System 2425

Mopier 8000

OCE 6535

QMS PrintSystem 2425

Source-Technologies ST 4024

TROY-Systems 624