Brother MFC 9970CDW - Manual (Page 202)

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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.
Duplex
Printing  Manual Duplex: Yes
 Automatic Duplex: Yes
 Paper Size
(Automatic Duplex): A4
 Paper Weight
(Automatic Duplex):
60 to 105 g/m
2
 Paper Type
(Automatic Duplex): Plain paper, Thin paper, Recycled paper or
Glossy paper