HP Deskjet 6620 Color Inkjet Printer - Manual (Page 81)

9.4 Automatic two-sided printing
To print a two-sided document automatically, one of the following accessories must
be attached to the printer:
Automatic Two-Sided Printing Accessory
Auto Two-Sided Print Accessory with Small Paper Tray
The two-sided printing accessories only support certain paper types. For a list of
supported paper types, see the documentation that came with the accessory.
Printing
Follow these instructions to print a two-sided document:
1. Open the Print dialog box, and then select the Two-Sided Printing panel.
2. Select the appropriate binding:
HP Deskjet 6600 series printer User's Guide
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