Cartridge compatible with Lexmark C540/C544, C540H2KG Compatible Black Toner Cart - Walmart.com
Amazon.com: Lexmark C540, C543, C544, C546, X543, X544, X546 Series High Yield Black Return Program Toner Cartridge (2,500 Yield), Part Number C540H1KG : Office Products
Lexmark Black & Color Imaging Kit for X543 & X544 Series MFPs & (C540X74G)