With the tag line ‘out of sight, but not out of reach’, you can pretty much gather what the intended purpose of this gadget is, and a very good gadget it is indeed. If you’re like me and prefer your workspace clutter free and clean, with plenty of room to swing whatever you like, then the BackPack™ might just be your savior. Use it to hold external hard drives as an easy place to keep whilst backing up, leave your iPhone sitting pretty, or keep a secret stash of moonpies on it if you really wish (Twelve South recommend Transformers).
I’ll leave the technological talk to the folks at Twelve South to explain how the shelf works:
The BackPack rests on the back of the desk stand on flat-screen iMacs and Apple Cinema Displays using gravity and two simple, adjustable clips. This allows you to position the sporty shelves at the perfect height without a screw ever touching your iMac. Because the BackPack uses gravity to stay in place, it will not leave any scratches or marks on your machine.
via Geeky Gadgets