what is LED ?

LED stands for "light emitting diode." A diode is an electrical component with two terminals which conduct the electricity only in one direction. With an electrical current, the diode emits a bright light around the small bulb. Typically, diodes have been used in many technologies such as radios, televisions and computers as an electrical component for conduction.

Connecting a diode to an electrical current excites the electrons within the diode, making them release photons, which we see as light. The color of the light is a direct result of the energy gap in the semiconductor of the diode. This means that LEDs produce a spectrum of colors easily and brightly while using very little electricity to do so. 

In the search for energy-efficient lighting, LEDs have proven to be the most efficient bulbs available. Energy Star--rated LEDs use at least 75 percent less energy than traditional incandescent bulbs and last 25 times longer, according to the U.S. Department of Energy. LEDs even outdo CFL (compact fluorescent lighting) bulbs in efficiency, primarily because they have twice the lifespan of CFLs. LEDs are more efficient than both incandescents and CFLs because they emit light in a targeted direction --- instead of scattering it in all directions --- and they don't require or emit great amounts of heat. Incandescents and CFLs release most of their energy as heat --- 90 percent and 80 percent, respectively. 

The biggest problem for consumers when purchasing LEDs for residential lighting is the upfront cost. Depending upon the size and brand of the bulb, LEDs can cost two to six times the price of CFLs. When replacing bulbs for multiple lighting fixtures, the idea of spending hundreds of dollars on bulbs deters many potential customers. However, LED production is not only improving but increasing, which will mean greater affordability for consumers in the near future.
Here is one led light bar,this light bar is for off road ,4*4, SUV and others car,as anyone need.

LED light bar