There are 3 silver and one black drive, all including USB to usb as well as e-sata cable. There is only one power supply total. Backstory is that I bought a bunch of thing from a photographer closing his studio. While I wanted to make these work, I ended up with a larger array that suits my needs better. The good thing about these is they're hard RAID, so no subscriptions to buggy software. Let me know if I can answer more questions!
3tb pressure test from Blackmagic disk speed test was hovering around 170-200 mbps read and write for the two drives I tested.
From manufacture:TheMobileSTOR MS4UT+is a 4-bay hardware RAID 5 storage tower that utilizes high performance USB 3.0 and eSATA interfaces to provide over 200MB/s in performance. The included USB 3.0 port is backwards compatible with widely available USB 2.0 ports, which is a convenient feature when both USB 3.0 and eSATA connections are unavailable. With built-in RAID 0, 1, 10, 3, 5 and spanning, the MS4UT+ provides hardware RAID redundancy protection against hard drive failures. The RAID engine is embedded within the enclosure and performs all RAID parity calculation to reduce CPU utilization from the host PC. RAID controller cards are unnecessary. Four hot-swappable hard drives slots are behind the front cover to allow easy trouble shooting and hard drive replacement. The newly trayless design allow easy installation. With adjustable cooling fan design, and high performance transfer rate to support various audio and video editing problems, MS4UT+ is the ideal storage tower for high-end computing.