License plate bulbs are used to illuminate the rear license plate on your vehicle. From the factory, the bulbs are incandescent, lighting up in a yellowish color.Newer luxury cars use LED modules to illuminate the license plate with modern, cool white light. By changing your license plate bulbs to LED, you can easily add this luxury look to your vehicle! The installation is 100% plug-and-play, just replace your factory bulb. Cool White recommended for on-road cars.