Synology DX525 5-Bay SATA Expansion Unit

The Synology DX525 adds five drive bays to selected 25-series DiskStation models, helping users expand storage as their data grows. It accepts 3.5-inch SATA hard drives and 2.5-inch SATA SSDs, with hot-swappable trays for maintenance and expansion. The unit connects through its dedicated expansion port and is managed through the host NAS and Synology DiskStation Manager. It can be configured as additional storage or as a separate local backup destination, depending on the host model and DSM setup. Compatible host models listed by Synology include DS925+, DS1525+, DS1825+, DS725+ and their supported variants; compatibility should be checked before purchase because the DX525 is not a universal NAS accessory. The expansion unit is diskless: drives are sold separately, and Synology advises consulting the current compatibility list before buying them. Performance and usable capacity depend on the host, selected drives, volume design and RAID configuration.