These printers use the 78C1XK0 cartridge:
Lexmark CS 421
Lexmark CS 421 DN
Lexmark CS 521
Lexmark CS 521 DN
Lexmark CS 622
Lexmark CS 622 DE
Lexmark CX 421
Lexmark CX 421 ADN
Lexmark CX 522
Lexmark CX 522 ADE
Lexmark CX 622
Lexmark CX 622 ADE
Lexmark CX 625
Lexmark CX 625 ADE
Lexmark CX 625 ADHE