Brother HL-7050 Series User Manual page 134

Sorter
When you want to print a lot of copies of a document, you can print
each copy and direct it to the bin that you want. You will not have to
sort the copies after printing them.
Stacker
You can print large print jobs when no one is in the office. You can
print 100 sheets of plain paper to each bin of the mailbox. When you
remove bins 2, 4, 7 and 9, the total output increases to 1900 sheets
(including the printer output tray).
OPTIONS 4 - 7