Cold Cathode Fluorescent Lamp, or CCFL, backlights offer low power consumption and a very bright white light. The primary CCFL configuration used in LCD backlighting is edge lighting. A cold cathode fluorescent lamp is the light source with a diffuser distributing the light evenly across the viewing area. CCFLs require an inverter to supply the 270 to 300 VAC @ 35KHz used by the CCFL tube. They are used primarily in graphic LCDs and have a longer life - 10,000 to 20,000 hours - than EL backlights do. Their biggest drawbacks are: cold weather will reduce the light output by as much as 60%, they require an inverter to generate the 350VAC please note that the inverters do not function well at low temperatures, the light intensity cannot be varied (it is either on or off), and vibration can reduce the life expectancy of up to 50%.