The Addonics 5X1 eSATA Port Multiplier (PM) and eSATA Port Multiplier for Rackmount Systems enables SATA hard drives to be configured for a wide range of storage applications. Build to fit perfectly into the Addonics Storage Tower and many standard 2 bay or larger SCSI enclosures, these Port Multipliers can combine up to 5 SATA hard drives into one eSATA connection. The 5 drives can be set up as individual drives, as RAID set or with JBOD to become one large hard drive depending on the controller. When multiple PMs are combined with Addonics 4-Port eSATA controller, you can attach externally a whopping 20 SATA hard drives to your computer via 1 controller!