The S3540BU33E 4-Bay HDD enclosure lets you install four 3.5” SATA hard drives into an external enclosure, and connect to your computer through USB 3.0 or e SATA. For fast performance & efficient data transfers, the enclosure supports SATA III transfer speeds -- up to 6 Gbps when connected through e SATA. The versatile enclosure can also be connected through USB (Universal Serial Bus) 3.0, with support for UASP, performing up to 70% faster than conventional USB (Universal Serial Bus) 3.0 when paired with a UASP-enabled host controller. See our UASP testing results below for further details. To ensure compatibility with your computer system, the S3540BU33E supports all of the leading operating systems, including: Microsoft Windows (8/7/ Vista/XP/ Server 2008/ Server 2003), Apple OSX (10.9/10.8/10.7/10.6), Linux, & Google Chrome OS™. The S3540BU33E is backed by a Star Tech.com 2-year warranty & free lifetime technical support. enhanced Performance with UASP UASP is supported in Windows 8, Mac OSX (10.8 or above), & Linux. In testing, UASP performs with a 70% faster read speed & 40% faster write speed over traditional USB (Universal Serial Bus) 3.0 at peak performance.