Dip beams are HID (High Intensity Discharge) and are controlled by a ballast and an ECU. The bulbs act in the same way as an arc lamp,--- there is no filament just a gas and 20,000+ volts.(there's a warning label)! The bulbs are very expensive (you can buy cheap not-recommended Chinese ones) but they last a very very long time, like almost the life of the car. When you start your car, if you switch on your headlights facing a white garage door for instance, you should be able to see the headlight adjuster working to bring the beams up to the correct height. Hope this helps.