Synology RX1217SAS 12-Bay Rackmount Expansion Unit (SYN-RX1217SAS) - Drive Bays: 12, Compatible Drive Type: 3.5" SAS HDD, 2.5" SAS HDD, 2.5" SAS SSD, 3.5" SATA HDD, 2.5" SATA SSD, External Ports: 1 x SAS IN-port, 1 x SAS OUT-port, 500W Power Supply