How can I transfer files to / from USB Disk?

USB file transfers with iTunes is the fastest way to transfer files. If you are using USB Disk Pro you can also transfer files wirelessly (see questions bellow). Here is how to use the "File Sharing" section in iTunes:

If you are transferring protected files to your computer, make sure your device stays unlocked (with the screen on) during the transfer. See this page for more details on how to use "File Sharing" in iTunes:https://support.apple.com/kb/HT4094.