You can install one yourself. Any 2 1/2 inch with SATA connection, whether spindle disc or SSD.

...the question arises as to why you want to do this with an obviously new device that has an HD installed which is absolutely more than sufficient for "normal" use.

if you are already using a cloud key plus or other ui products (running a ukk2 alone makes no sense) then you surely know that the ui community has the answers.