I use the Backpack for ext. Hard drive. Did it not therefore mounted behind the base of the Mac but between walking and device. That's good. You do not see the disk for Time Machine and it does to a safe place in service. Design fits perfectly to the Mac but is a bit pricey for a piece of perforated plate and two screws. But we already know Mac owners yes :-) The USB 3.0 hard drive from WD interferes with the BT and W Lan reception in any way although it is very close to the unit. I have heard such interference by some users.
