Apple iPod nano (6th generation) - Manual (Page 9)

5 Disconnect the cable from iPod nano when you’re ready to use it.
Don’t disconnect iPod nano if you see the “Connected” or “Synchronizing” message. To avoid
damaging files on iPod nano, eject iPod nano before disconnecting.
For more information about safely disconnecting iPod nano, see “Disconnecting iPod nano from
your computer” on page 13.
9 Chapter 2 Getting started