It’s called Elasty and it was created by designer Yoori Koo. It’s a silicone bumper fitted with elastic strips which allow you to stash your headphones, pens, cards etc. on the back of the phone. smart!
Awesome Bookcase Design. Tail Conditional Expectation for Multivariate Pareto Portfolio: TCE-Based Capital Allocation in the Case of Multivariate Pareto Distribution by Arthur Chiragiev and Zinoviy Landsman http://www.amazon.com/Conditional-Expectation-Multivariate-Pareto-Portfolio/dp/383831557X/ref=sr_1_1?s=books&ie=UTF8&qid=1393182917&sr=1-1