This is a bit of a niche product and I'm not sure how much stock they have, but this seems to be a great price for this product. StaticIce, NewEgg, and eBay all put this product around $1000 or higher.
Based on my research it likely contains a SanDisk X600 SSD (which I believe has a DRAM cache) and is apparently similar performance to a WD Blue SSD… so the SSD alone inside these drives would be valued at $400ish.
The on-board system supports PLEX, DLNA, and backing up of SD cards/USB drives.
Keep in mind this does appear to be somewhat EOL and there hasn't been a firmware update all year (but maybe that's just coz it's perfect already).
https://www.amazon.com.au/SanDisk-2TB-Extreme-Portable-SDSSD…
Jees $275 extra for wireless