Genuine OEM Lexmark X522 Toners
The X522's toner options differ in both capacity and intended use. High-yield 12A6735 black toner gives you more printing between changes than the smaller 12A6830 cartridge. The 12A6839 cartridge is intended for labels, so it is a use-specific choice rather than just another larger cartridge.
Toner Buzz carries genuine Lexmark black toner for the X522, including those options and high-yield 12A6835 toner. Check the Return Program terms when choosing: cartridges sold under that program are for single use and must be returned to Lexmark when empty.