The auto-dimming rear view mirror offers greater safety when driving at night, as it stops you from being dazzled by traffic travelling behind. It consists of a mirror element and an electronic system that detects light from in front and behind by means of photo sensors. If the amount of light from behind is greater than that in front, the mirror is darkened. The surface of the mirror features a layer of electrolytes, similar to the LCD display of a mobile phone. The electrolytes consist of uniform crystals. When a voltage is applied, the crystals arrange themselves at a given angle, determining how much light is reflected. The strength of the voltage determines to what extent the mirror is darkened.