These printers use the C544X2MG (High Yield) cartridge:
Lexmark C 540 DW
Lexmark C 544
Lexmark C 544 DN
Lexmark C 544 DTN
Lexmark C 544 DW
Lexmark C 544 N
Lexmark X 544
Lexmark X 544 DN
Lexmark X 544 DTN
Lexmark X 544 DW
Lexmark X 544 N
Lexmark X 548 DE
Lexmark X 548 DTE