The Synology DX517 expansion unit connects to compatible DiskStations via an eSATA port and supports up to five 2.5" or 3.5" SATA hard drives or SSDs. It allows RAID volumes to be expanded without downtime, while drives can be installed or replaced without powering off the unit. It can also create a separate volume for local backups and works with DiskStation Manager.

• Type: Expansion unit
• Drive bays: 5
• Supported drives: 2.5" or 3.5" SATA HDDs or SSDs
• Ports: 1 eSATA
• Compatibility: DS1817+, DS1618+, DS1517+, DS918+, DS718+, DS1817, DS1517, NVR1218
• Software: DiskStation Manager (DSM)
• Power supply: 200 W
• AC input voltage: 100–240 V
• Power consumption: 29.9 W in operation, 2.4 W in HDD hibernation
• Operating temperature: 5–40 °C
• Storage temperature: -10–70 °C
• Noise level: 21.5 dB(A) at idle with full capacity
• Dimensions: 15.7 × 24.8 × 23.3 cm
• Weight: approx. 3.91 kg
• Quantity: 1