It's currently configured to 15TB as it's in RAID 5 configuration, allowing for a drive failure without suffering data loss. This can be reconfigured in the Pegasus2 Series Utility to whichever RAID type required.

Included with the power supply and Thunderbolt 2 cable. A Thunderbolt 3 to Thunderbolt 2 adapter will allow this to work with the latest equipment, without saturating the data bandwidth of Thunderbolt 2.

The enclosure is used, so has a few marks, as visible from the images.