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... genius for the gym or whatever!
Genius...Lay out your gallery arrangement. Flip frames over. Mark hanger/nail spot on several pieces of wax paper taped together. Flip waxed paper over, tape to wall, nail into wall where indicated. Remove waxed paper. Hang photos.