[RX1217RP] Synology Expansion Unit (Rack 2U) for RS2416(RP)+ , RS3617xs, RS3617RPxs, RS3617xs+, RS4017xs+ / up to 12hot plug HDDs SATA(3,5' or 2,5')/2xRPS incl Cbl
[RX1217] Synology Expansion Unit (Rack 2U) for RS2416(RP)+ , RS3617xs, RS3617RPxs, RS3617xs+ , RS4017xs+ / up to 12hot plug HDDs SATA(3,5' or 2,5')/1xPS incl Cbl
[RX418] Synology Expansion Unit (Rack 1U) for RS818+, RS818RP+, RS816, RS815+, RS815RP+, RS815 up to 4hot plug HDDs SATA(3,5' or 2,5')/1xPS incl eSATA Cbl