The Synology DX517 is a 5-bay expansion enclosure designed for flexible storage scalability with compatible Synology DiskStation models including DS1823xs+, DS1821+, DS1621xs+, DS1520+, DS1819+, and many others across 15-23 series. Supporting both 3.5" and 2.5" SATA hard drives and SSDs with hot-swappable, screwless drive trays for easy installation and replacement without powering down. Connects via eSATA port with included expansion cable for seamless integration and immediate recognition through DiskStation Manager (DSM). Enables online volume expansion without interrupting storage or services on the host NAS, or serves as a dedicated local backup destination when created as a separate volume for protection against system failure. Managed directly from DSM on the host NAS for unified drive management and monitoring. Hot-swappable design reduces setup time and allows for maintenance without downtime. Ideal for businesses and power users requiring on-the-fly capacity expansion for file servers, backup repositories, and growing data storage needs. Includes AC power cord, eSATA expansion cable, and accessory pack. Backed by Synology's 3-year limited warranty.