Flex light uses a frontlight instead of a backlight. This is done by laminating a FLEx Illuminated Optical Film layer over the top of the screen which is then lit using 1 or 2 LED's. The film behaves like a light guide. It will also work with color displays and can be turned on or off as needed. FLEx’s light guide film is completely invisible when turned off yet produces a soft, uniform glow for front lighting reflective displays, such as eBook readers. It will only add .05mm to the thickness of the display.