HX4 external disk array from Vantec. This unit is new except that I have added 4 x 1.5TB hard drives to it. So it had to be tested. It will make an ideal backup device for a workstation or for movie storage. The unit has been set up as a software Raid 5 giving 4.5TB of usable storage. A CD is included giving instructions on how to create and manage the software Raid 5. It was created under Windows 10. It may work on Win 8.1 but I don't think it does on Win 7. However feel free to check this. The Raid 5 is Microsoft's implementation. I have also added a handle to the top of the case to make movement easier. I am selling this because I ended up buying the wrong device and have no use for this one. I decided to add drives since they were lying around doing nothing otherwise. The drives are used but have all been tested thoroughly so I have no reason to suspect they will fail soon. One of the advantages of Raid 5 is that you can have a drive fail but still read all your data until you fix the failed drive. To replace a failed drive you would use a 2TB unit. The case has USB 3.0 and eSATA inputs.