Update: LG has now teased the phone during its CES 2021 press conference and it appears to be called the LG Rollable. Will it be with us later in the year?
LG isn't the first company to show one - both TCL and Oppo have also shown off rollable phone concepts previously, while Samsung has long demonstrated flexible display tech.
There are few details about "Project B" which appears to be the working title for the new device, but we have some initial details via a forum post. We don't know if the images here are official renders or not, unfortunately, but in any case they give a good flavour of the device.
We also have some additional details on the size and resolution of the display too - both when rolled and unrolled - the post claims the device will have a 6.8-inch 2,428 x 1,080 display that rolls out to a 7.14-inch 2,428 x1,600 display. So it'll be the same size and orientation as a traditional smartphone until it's unrolled.
According to Slashgear, other leaks suggest the device has a 4,200 mAh battery and 16GB of RAM, though as the site notes, 16GB of RAM seems way too much since even flagship LG phones tend not to have high-end specs like that.