Brother MFC-8440 User Manual page 187

Use Duplex Unit (For MFC-8840D)
Check the Duplex box and then select Use Duplex Unit. In this
mode the MFC prints on both sides of the paper automatically.
Manual Duplex
Check the Duplex box and then select Manual Duplex. In this mode,
the MFC prints all the even numbered pages first. Then the printer
driver stops and shows the instructions required to re-install the
paper. When you click OK the odd numbered pages are printed.
Duplex Type
You can select Duplex Type. There are six types of duplex
directions available for each orientation.
Flip on Left Edge
Flip on Right Edge
Flip on Top Edge
Flip on Bottom Edge
Flip on Top Edge (No Reverse)
Flip on Bottom Edge (No Reverse)
Binding Offset
Check the Binding Offset option, you can specify the offset value of
the binding side in inches or millimeters (0 - 8 inches) [0 - 203.2 mm].
12 - 7 PRINTER DRIVER SETTINGS