Synology RackStation 12 Bay Expansion Unit (Synology RX1217RP) - Drive Bays: 12, AC Input Power Voltage: 100 V to 240 V AC, Power Frequency: 50/60 Hz, Single Phase, System Fan: 80 mm x 80 mm x 3 pcs, External Ports: 1 x Expansion Port, Applied Models: RS1619xs+; RS3618xs; RS2818RP+; RS2418RP+; RS4017xs+; Redundant Power Supply