https://www.theverge.com/2019/10/22/20926719/lg-g8x-dual-screen-spÄecs-features-price-release-date-us-announced
The G8X ThinQ is a unique take on a dual-screen phone. Instead of using a foldable screen, like Samsung’s Galaxy Fold, or attaching an entire second screen with a hinge, like Microsoft’s upcoming Surface Duo, LG just made a normal phone with one screen. The second screen is based entirely within a case that the G8X slips into. Once it’s in, you can turn the second screen on and off or remove the phone later and just use the device as normal.