So far, a variety of H4 car bulbs have appeared in the HID market. Through market research, analysis, and exchanges and discussions with peers, it is concluded that these products have their own advantages and disadvantages. The following is an analysis of them:

　　H4-1, this type of lamp head is called single light, single xenon, etc. It is characterized by the cheapest price, simple installation, and good condensing effect of single light; Adverse effects of driving and annual inspection;

　　H4-2, mono-ammonia mono-halogen, or a xenon-halogen lamp, its characteristics are that the price is similar to that of a single light, and the gas lamp has a better condensing effect. Ashamed, the installation is relatively simple; at the same time, since the service life of the halogen lamp is theoretically only 1/10 of that of the xenon lamp, the halogen lamp needs to be replaced frequently during use;

　　H4-3, bi-xenon or double tube, is characterized by using two lamps to realize the change of far and low beams (high and low lights), requiring four ballasts, so the price is the most expensive and the installation is more complicated;

　　H4-4, lifting and shrinking lamp or both high and low beam light, uses a xenon lamp to expand and contract back and forth to change the position of its light-emitting point, so as to achieve the purpose of changing the light of far and near beams. Its characteristic is that the far and near beams are all xenon lamps. , the price is moderate, and there is no short-term loss of light when dimming, it is an ideal solution.