The H4 car bulb is used for headlights, it contains two filaments, and you can choose a high beam and low beam in one bulb. So if your car is suitable for H4, you only need one set of bulbs to achieve the effect of high beam and low beam. If using other types of headlights, you will need to purchase 2 sets, one for high beam and one for low beam.

　　This bulb has a three-prong attachment on the harness which makes it unique among other bulbs such as H1, and H7... having 2 prongs on the base. Therefore, they are easier to identify.

　　The H4 car bulb was originally invented for European racing. Decades later, H4 became popular in the United States, but only on motorcycles, not cars and trucks. Regulators in the United States have banned their use because they can easily blind oncoming drivers and cause traffic accidents, and twin-filament bulbs are not precise enough to meet the limits of headlight beam patterns.

　　To remedy this deficiency, HB2 or 9003 was developed. In fact, the H4, HB2, and 9003 are all essentially the same bulb and can be used interchangeably. So we can see in the market that these three types of labels will be marked on the packaging of many light bulbs.

　　Halogen H4 Headlight bulb is a traditional car bulb. They are usually produced with yellow lights. They are the cheapest lights compared to HID, Xenon, and led headlights.

　　H4 LED headlights are more expensive than halogen bulbs but last longer. They have a cooler color temperature, appearing in bright white or blue, which is more prominent and makes your car more stylish. Plus, they don't require ballasts to control them, meaning faster, easier to install, and more convenient to use.

　　Haining Suez Car Lights Co., Ltd. is a car Bulb Manufacturer, its main products are HID car xenon lights, etc. Welcome to consult!