ah...well strange thing, only in how certain things are viewed

that item is a hot swappable drive, like I mentioned....the only caveat is you have to have a system or setup that handles that...that looks to be made for server type contructions
a typical vanilla case will not have the ability to service that drive...however it is not something so out of the realm...just needs the right hardware for the case
Live Search: hot swap drive bay
from the above link, first search matches what I wanted to illustrate
4-Bay eSATA Hot Swap RAID Drive Enclosure
and alternative
Raid Back-Plane Aluminum Serial ATA Hot Swap 3-4 Drive Bay Converter
one is an enclosure, much like a mini tower just to house the hot swappables...the other is a drive bay converter...to allow the space in your tower to hold hot swappables...you would need a tower that has space for 3 external 5.25 bays.
if this would be too much hassle...just get a standard external harddrive