This could be a rear panel for the coming refresh of the iPhone SE (2017). As you can see, no dual camera and looks to be bigger than 4-inch. Looks more like 4.7-inch, so my guess is that they will use a shell more like the old iPhone 6 this time, instead of the shell of the old iPhone 5s. That's only logical to me. One strange thing though, is the thing at the bottom of the back that looks like a Touch ID button...
Via Slashleaks
Via Slashleaks