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