Why is this so small?

Alternatively, why aren't they all so small?
Less than 4" x 1 1/4" x 1/3".

Is it a real HDD, a spinner, with a rotating platter? It calls it a
harddrive more than once, and never uses SSD, etc. but it's so small.

https://www.amazon.com/External-Hard...9&sr=1-11&th=1

What about that it has no brand name? Would you buy it for a backup
drive?


For file backup, is a real 2.5" external drive better for backup?
external 2.5" HDD, SSD, 3.5" HDD in a dock