Epson B 310N - Manual (Page 63)

Printing with Special Layout Options 63
3. Make sure that Duplexer Installed is displayed in the Auto Duplex Printing Information
section, and then click OK.
4. Close the EPSON Printer Utility3 dialog.
5. Access the Print dialog.
& See “Accessing the Printer Driver for Mac OS X” on page 15.
6. Click the d button to extend this dialog.