The HP Color LaserJet Enterprise M551dn printer uses either the standard yield CE400A, CE401A, CE402A, CE403A (HP 507A) or the high yield CE400X (HP 507X) laser toner cartridge. Toner Refill Store's premium toner cartridges are 100% guaranteed to meet or exceed your expectations and surpass the print quality of the OEM (Original Equipment Manufacturer) HP Color LaserJet Enterprise M551dn. We also carry numerous compatible and remanufactured HP inkjet cartridges. This HP Printer uses either a High Yield cartridge or Standard Yield cartridge. The High Yield cartridge will have an 'X' and the standard yield an 'A' at the end of the cartridge number. Toner Refill Store carries both the High Yield toner cartridges and toner refills for the HP CE400X and the Standard Yield toner cartridges and toner refills for the CE400A, CE401A, CE402A and CE403A. Our HP Color LaserJet Enterprise M551dn high yield laser toner cartridges have a 'One Year 100% Satisfaction Guarantee'. The use of our premium compatible laser toner cartridges for the HP Color LaserJet Enterprise M551dn does not void your printer's warranty.