Oki B840n User Manual page 32

> Envelopes should be loaded flap down, face up with the top edge to the left and
short edge into the printer.
NOTE
Do not select Duplex printing on envelopes.
> Load Transparencies face up and top edge into the printer.
> For heavyweight paper or cardstock open the rear stacker to collect the printed
output. This will give the paper a nearly straight path through the machine,
avoiding paper jams and damage to the paper.
3. If required, set the media size and orientation in the media menu using the control
panel, then issue the print command.
Damage to the printer may occur if the incorrect paper setting is
used when printing on a different media.
NOTE
> You can also set the media type in your printer driver. However, the
printer driver settings will override the settings on the control panel.
> Remember to reset the printer for normal paper after printing on a
different media.
CAUTION!
Paper recommendations > 32