It was designed to lessen the contrast and brightness of the original PRUSA LCD which has very bright blue screen. It doesn't block the blue light by 100%, but it looks better with orange tint. The user could add more optical film on it with ease.
In addition, it doesn't hurt the view angle. I carefully integrated tilted side view slope inside.
Yes, it's the world's 1st optical LCD filter for the 3D printers.