StarTech.com 4 Bay External Hard Drive Array RAID Tower with eSATA USB 3.0 Enclosure (SAT3540U3ER) Support for up to 4 drives provide large amounts of storage with a choice of high speed interfaces from USB 3.0 or eSATA The removable front cover and accessible drive bays allows drives to be replaced easily in case of failure or a system upgrade Built-in support for numerous RAID modes for most personal/business needs and an 80mm controllable cooling fan to keep drives from overheating SuperSpeed USB 3.0 host interface, with transfer rates up to 5 Gbps SATA revision 2 compliant eSATA host interface, supporting transfer rates up to 3.0Gbps Supported RAID modes: 0 (stripe), 1 (mirror), 3 (parity disk), 5 (striped parity), 10 (1+0), Span/Concatenation User-configurable, directly from the unit itself 80mm cooling fan with 4 selectable speeds: Low, Med, High, Auto