Its called a Backpack.
Sounds like the Lumia 920 is the Chuck Norris of phones? Yeah that's right, I went there...
Chuck Norris actually built the Lumia 920 by hand, each and every one of them. And he built them all next week, but because he built them so fast it opened a time-space continuum portal that allowed the devices to travel back in time and be sold a week before they were made.