For great quality prints and reliable operation from your OKI B731/MB770 laser printers, install a genuine OKI Black Toner Cartridge. You'll notice faded text and foggy backgrounds on prints when the current toner cartridge is running low. Order a replacement cartridge as soon as possible and replace it when you see the Toner Empty message on your printer. This toner cartridge is packed with enough black toner to print 36,000 pages.