These printers use the 56F1U00 cartridge:
Click On a Printer to View it's Cartridges
          Lexmark MS 521
          Lexmark MS 521 DN
          Lexmark MS 621
          Lexmark MS 621 DN
          Lexmark MS 622
          Lexmark MS 622 DE
          Lexmark MX 521
          Lexmark MX 521 ADE
          Lexmark MX 521 DE
          Lexmark MX 522 ADHE
          Lexmark MX 622 ADE
          Lexmark MX 622 ADHE