The s3520bu33er 2 bay raid enclosure offers a high performance external storage solution enabling you to build a secure raid array with two 35 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 as well as full usb 30 transfer speeds when connected through usb the enclosure supports uasp w