Synology RackStation 12 Bay SAS Expansion Unit (Synology RX1217sas) - Drive Bays: 12, AC Input Power Voltage: 100 V to 240 V AC, Power Frequency: 50/60 Hz, Single Phase, System Fan: 60 mm x 60 mm x 4 pcs, External Ports: 1 x SAS IN-port, 1 x SAS OUT-port, Applied Models: FS6400; FS3600; FS3400; SA3600; SA3400; RS18017xs+, Redundant Power Supply (for RP model)