These types of lights used to be more popular on most European vehicles, but are becoming common on other makes and models. Projector lights are lights that have a filament located at one focus of a reflector, and a round glass or heavy duty plastic condenser lens at the front of the lamp. These lenses in front of the light bulb distribute the light evenly across the front of the vehicle, and can give a larger range of visibility for the driver. The bulbs themselves are usually common Halogen bulbs that can easily be changed.