Install the automatic two-sided printing accessory (duplexer)
You can print on both sides of a sheet of paper automatically. For information on using
the duplexer, see Print on both sides (duplexing).
To install the duplexer
Slide the duplexer into the back of the printer until the unit locks into place. Do not
press the buttons on either side of the duplexer when installing the unit; use them
only for removing the unit from the printer.