Turn 2 SATA hard drives into external RAID storage, connected through USB (Universal Serial Bus) 3.0. The SAT3520U3SR USB (Universal Serial Bus) 3.0 RAID Enclosure turns two 3.5" SATA (SATA I, SATA II, SATA III) hard drives into an external RAID array through a USB (Universal Serial Bus) 3.0 connection. Large capacity drives (tested with up to 4 TB per bay) can be used to greatly enhance your computer storage/backup capabilities.