This is a Synology 12-bay expansion unit (the RX1217RP family) used to add extra drive capacity to an existing Synology rackmount NAS, rather than a standalone server — it has no processor or OS of its own and connects to a host RackStation via an eSATA expansion cable. It's compatible with Synology's RS1619xs+, RS3618xs, RS2818RP+, RS2418RP+ and RS4017xs+ enterprise NAS units, letting an IT team grow storage well beyond the base unit's own bay count (typically doubling it) without replacing the whole NAS. This unit includes a redundant, hot-swappable power supply, matching the resiliency expectations of the business-critical NAS models it's designed to attach to. Buyers should confirm their specific RackStation model and firmware support this expansion unit before ordering — drives themselves are sold separately.