Brother MFC-8660DN - Manual (Page 180)

166
Consumable items
1 When printing Letter or A4 size paper at 5% print coverage
Toner Cartridge Life
TN-550: Standard Toner Cartridge: Approx. 3,500 pages
1
TN-580: High-Yield Toner Cartridge: Approx. 7,000 pages
1
Drum Unit Life Expectancy DR-520: Approx. 25,000 pages