Synology DX5 5-Bay Plug-n-Use Storage Box to Add Disks to DS509+ NAS (Black) Disk Station Manager 2.1: AJAX-Based Management Interface, Remote File Management with a Web Browser, Max HDD Support (Internal HDD): 5x 2TB Internal HDD: 5X 3.5?SATA(II) and External HDD Interface: 1X eSATA Networking Protocols: CIFS, AFP (3.1), FTP, NFS, Telnet/SSH The DX5 requires the usage of the DS509+.The DX5 will not operate by itself