3 Key Expansion Features of the DS1520+

eSATA expansion for up to 10 extra bays The DS1520+ supports two DX517 expansion units over eSATA, adding 10 more drive bays.

PCIe slot for network or storage upgrades A PCIe 2.0 x2 slot lets you install a 10GbE network card or an M.2 NVMe adapter.

Limited PCIe bandwidth The PCIe 2.0 x2 slot offers only 2 lanes, so high-speed add-ons may not reach full performance.