Quickly make second monitor dark without turning it off when playin some atmospheric game or watching some movie that turned out to be worth of doing so
Trying to save electricity, reduce carbon emission.
To put on my 4 monitors when I go to sleep, instead of putting them to sleep.
Easier to see spots when I'm wiping off my screen
Background for a game. Screen is too big, 3440x1440. Don't like to play it that big, so i do 2560x1440. Need black bezels at both sides.