The Lexmark 50F1000 Unison Printer Cartridge Toner in black is a high-yield toner designed for use with various Lexmark printer models. This cartridge is compatible with printers such as Lexmark MX321adw, MS421dn, MS321dn, MX521ade, MS521dn, MS621dn, MS421dw, MX521de, and MS622de. With a weight of 1 lb., this Lexmark cartridge is an ideal choice for those looking for reliable and efficient printing supplies.