Akitio NT2U3 USB 3.0 Dual Bay RAID Enclosure Compact & Screw-less Design; 2-Bay RAID Storage Enclosure Configurable RAID function (Non-RAID, RAID 0, RAID 1) Built-in low speed (2800RPM) fan for extra cooling Due to the OS limitation, Windows XP only support up to 2 TB (maximum), Windows Vista and Windows 7 will support more than 4 TB. USB 3.0 is currently not available for the Mac but the device can still be used with the older USB 2.0 connection