FreeAgent Desk/Xtreme drives do not have a power switch.
Most users assume that a power switch means that an external drive can be shutdown at anytime a computer is powered on. This is not the case; all external disk drives must be properly disconnected from a computer to prevent data corruption and/or loss. To do this, users must either:
Use Windows' Safely Remove feature to disconnect an external drive
(See here to see how to safely remove an external drive in Windows.
Properly eject an external drive from a Macintosh computer by dragging the drive icon to the Trash can.
(See here to see how to safely remove an external drive in Macintosh.
In conclusion, a power switch is thus an unnecessary, redundant component.