The s3520bu33er 2 bay raid enclosure offers a high performance external storage solution enabling you to build a secure raid array with two 35rdquo sata hard drives with the option to connect it to your computer through either an available usb 30 or esata port for fast data transfers and efficient performance from your sata iii drives the raid enclosure supports full sata iii transfer speeds up to 6 gbps as well as full usb 30 transfer speeds up to 5gbps when connected through usb