RX1217sas (Redundant Power Supply) 12-Bay Expansion (3.5" / 2.5" SATA or SAS) / 2U Rackmount / 1 x SAS-IN, 1 x SAS-OUT / 5 Years Warranty / Optional Rail Kit Sliding (RKS1317) Supported Models: FS6400, FS3400, FS3017*, FS2017, SA3600, SA3400, RS18017xs+ *Connecting to a Synology FS3017 requires the optional Expansion Card to be installed on the host device. FS3017 Expansion Card is sold separately.