Flip it open, and you have an ordinary, full colour clamshell. But closed, its “memory” LCD takes advantage of a low-power backside that’s black and white only.
This outer display can be programmed to support a number of apps and animations, but the most notable is definitely its rudimentary (but effective) self-portrait preview. Instead of displaying your actual face on the screen, you just see whether or not your mug is properly framed. (You know, before you flip open the phone to check yourself out in full colour.)