The iPhone has a beautiful retina display. But e-ink screens have their benefits. Thanks to popSLATE, you can carry your iPhone and still get a 4 inch e-ink display on the back as a second display for your phone. E-ink is a low-power technology, which means you can use this for a long time. This is a rugged case, so it does protect your phone too. A companion app is available for it as well. The case is available for as low as $79 at this point.