Brother  HL-4140CN User Manual page 155

Duplex  Manual Duplex:
Printing
Automatic Duplex:

 Paper Size
(Automatic Duplex):
 Paper Weight
(Automatic Duplex):
 Paper Type
(Automatic Duplex):
1
For labels, we recommend removing printed pages from the output paper tray immediately after they exit the machine
to avoid the possibility of smudging.
2 2
60 to 105 g/m for duplex print.
126
Yes
Yes
A4
2
60 to 105 g/m
Plain paper, Thin paper, Recycled paper or
Glossy paper