It is a single hard drive, but it pulls power over the USB. Not sure if the device you are connecting to will supply enough power. If you have a very low power USB jack, I suppose this may not function. You can get external enclosures that have external power supplies, but that makes them less portable so they are less common as an all in one portable drive. You may need to buy a separate drive and enclosure so you can ensure you get what you need.