These printers use the 841851 cartridge:

Ricoh MP C-3004 EX

Ricoh MP C-3504 EX

Ricoh MP C-4503

Ricoh MP C-4504

Ricoh MP C-4504 EX

Ricoh MP C-5503

Ricoh MP C-5504 EXSP

Ricoh MP C-5504 SP

Ricoh MP C-6003

Ricoh MP C-6004

Ricoh MP C-6004 EX