For small 2.5 "hard drives are not even needed the AC adapter yielding the same again can save space and weight when one knows in advance that it is a laptop.
The usage is very simple. All you need to do is connect the adapter to the SATA hard drive and then to insert these via USB cable to a laptop (in my case) or computer. The cable is though USB 3.0 is of course backwards compatible. From Windows 7, the hard drive will be recognized immediately without further Driver installation and you can access the hard drive. The access speed is how fast can I 3.0 copy the one without waiting long large amounts of data down by USB so.
For people who often need to save hard drives locally or do not have much storage space at home this little dock is perfect! I use at home, although still prefer my big dock but the way I take now only with this small!