Synology 12-Bay Diskless Plug-n-Use 2U Rackmount Expansion Unit (RX1214) Plug-n-Use Design for Seamless Storage Space Upgrade Online Volume Expansion SATA III 6Gb/s Interface Support Plug-n-Use Design for Seamless Storage Space Upgrade. Online Volume Expansion. SATA III 6Gb/s Interface Support. Energy-Saving Deep Sleep Mode. Easy Installation with Screw less Rail Kit (optional). Managed from Synology DiskStation Manager (DSM).