Bi-Xenon headlights use gas-discharge lamps that are electronically controlled. The arc unit contains a gas consisting largely of xenon, an inert gas, that is ignited by high-voltage. The resulting arc is very bright and serves as an excellent light source to illuminate the road. The spectrum of xenon light is much closer to daylight than conventional halogen, giving it a light blue-white color. Bi-Xenon headlights produce about twice as much light as comparable halogen headlights, and make night driving, particularly in poor weather, safer and less tiring for the driver's eyes.