Mediasonic HFR2-SU3S2 PRORAID 4 Bay 3.5" SATA Hard Drive Enclosure - USB 3.0 & eSATA Support 3.5" SATA I / II / III hard disk drive up to 12TB per drive, Support Hard Drive Transfer Rate up to SATA III Speed. Hardware Raid controller built-in on board with one-button control. One Button Raid Control support Single Drive Mode, Raid 0 (Spanning) JBOD, Raid 0 (Stripping), Raid 1 (Mirroring), Raid 3 (Stripped set with dedicated parity), Raid 5 (Stripped set with distributed parity), Raid 10 (Mirroring + Striping) Transfer rate up to 5.0Gbps via USB 3.0, up to 3.0Gbps via eSATA. Smart Fan with built-in thermal-sensor, Auto & Manual modes, and 3 speed levels Compatible with Mac OSX 10.8 or later and Windows 10 / 8.1 / 8 / 7 Support 3.5&#034; SATA I / II / III hard disk drive up to <span class="a-text-bold">12TB per drive</span>, and up to 4 x 12TB. (Not compatible with 4Kn Native Drives, and Power Disable feature HDD&#039;s) Example: WD / HGST Enterprise Drives. Support 2.5&#034; SATA SSD / HDD up to 10TB per drive.  (Adapter Bracket required, sold separately.) Hardware Raid controller built-in on board. Transfer rate up to 5.0Gbps via USB 3.0 and up to 3.0Gbps via eSATA (SATA II speed). Smart Fan with built-in temperature sensor, Auto &amp; Manual modes, and 3 speed levels Support S.M.A.R.T Support Power Synchronization with Computer. Single Mode: Computer will recognize 4 individual hard drives Raid 0 (Spanning) JBOD Raid 0 (Stripping) Raid 1 (Mirroring) Raid 3 (Stripped set with dedicated parity) Raid 5 (Stripped set with distributed parity) Raid 10 (Mirroring + Stripping) Auto and Manual mode to keep your drives cool. Manual mode has 3 level of fan speed selection USB 3.0 Transfer rate up to 5.0Gbps eSATA Transfer rate up to 3.0Gbps Enclosure is not default to any Raid mode.  Please set up your desired Raid Mode, or the enclosure will turn off after few seconds after it turned on. Raid mode confirmation button is at the back of the enclosure.  Please see picture on the left. If this unit is connected to eSATA port, please make sure your computer eSATA port support Port-Multiplier. Mediasonic strongly recommend user to install same capacity / model / brand of hard drive when you are setting Raid Mode. (Except Single Mode). User can download user manual and QIG from Technical Specification in Product information below. Windows 7 / 10 (32 / 64bit) (GPT Partition) Mac OSX 10.8 or later When this unit is in Raid Mode, the hard drive transfer rate is set at SATA 2 speed (3.0Gbps).  Therefore, the transfer rate for USB 3.0 / eSATA connection will be limited to 3.0Gbps. This limitation is due to the chipset, and no firmware fix. However, when this unit is in Single mode (4 independent hdd setting), the hard drive transfer rate will support SATA 3 speed, up to (5.0Gbps) for USB 3.0