The S352BU33RER 2-Bay RAID enclosure lets you build an external RAID array with two 3.5' SATA hard drives, and connect to your computer through USB 3.0 or eSATA. For fast performance and efficient data transfers, the enclosure supports SATA III transfer speeds -- up to 6 Gbps when connected through eSATA. The versatile RAID enclosure can also be connected through USB 3.0, with support for UASP, performing up to 70% faster than conventional USB 3.0 when paired with a UASP-enabled host controller. See our UASP testing results below for further details. The external RAID enclosure features a hardware RAID controller, supporting JBOD, Spanning, RAID 0, and RAID 1 -- to achieve greater drive capacity, or secure data redundancy. The RAID controller is also front mounted for ease of access when changing your RAID mode. For fast and easy drive installation and removal, the dual drive enclosure features a convenient trayless system that eliminates having to mount and fasten your drives, saving time and hassle.