Lexmark 56F1000 Standard Yield Compatible Toner- Black . Compatible with 56F1000 - Black. Fits Models: MS321dn, MS421dn, MS421dw, MS521dn, MS621dn, MS622de, MX321adn, MX321adw, MX421ade, MX521ade, MX521de, MX522adhe, MX622ade, MX622adhe