How to enable HP printer automatic duplex printing function in Windows 7
1) Go to Control Panel -> Devices and Printers -> Double HP Printer
2) Click "Customize your printer" in Printer Actions
2a) Or right click printer -> click "Printer properties"
3) Click the tab "Device Settings" -> Expand "Installable Options" -> Select "Installed" in "Duplex Unit (for 2-Sided Printing)
4) Now you can "Print on Both Sides"
