HP Deskjet 6127 Color Inkjet Printer - Manual (Page 26)

two-sided printing accessory (duplexer)
The duplexer is a special hardware feature that enables the printer to automatically print
on both sides of a page.
installing the duplexer
1. Push the two latch handles on the printer’s Rear Access Door toward each other,
then remove the door.
Caution! Do not discard the Rear Access Door. In order to print, the duplexer or the Rear
Access Door must be attached to the printer.
26