These printers use the C540H1CG cartridge:

Lexmark C 540

Lexmark C 540 DW

Lexmark C 540 N

Lexmark C 543

Lexmark C 543 DN

Lexmark C 544

Lexmark C 544 DN

Lexmark C 544 DTN

Lexmark C 544 DW

Lexmark C 544 N

Lexmark C 546 DTN

Lexmark X 543

Lexmark X 543 DN

Lexmark X 544

Lexmark X 544 DN

Lexmark X 544 DTN

Lexmark X 544 DW

Lexmark X 544 N

Lexmark X 546 DTN

Lexmark X 548 DE

Lexmark X 548 DTE