Apple AirPort Extreme 802.11n (4th Generation) - Manual (Page 18)

18 Chapter 2 AirPort Extreme Networks
Using the AirPort Extreme to Share USB Hard Disks
When you connect a USB hard disk to your AirPort Extreme, computers on the network
(wired and wireless) can access the hard disk to access, share, and store files.
It looks like this:
USB port d
2.4 or 5 GHz
2.4 or 5 GHz
Shared hard disk drive