Ourpick for the best halogen headlight bulb is the Philips 9006 CrystalVision Ultra Upgrade Bright White Headlight Bulb. The bulbs produce a bright white look similar to HID lights. The light Alumen is a measure of the total amount of visible light emitted by a source. The higher the lumen rating, the brighter the light. An H7 halogen bulb typically has a lumen rating of around 1500 lumens, while an H7 LED bulb can have a rating of up to 4000 lumens. This means that the H7 LED bulb is significantly brighter than the H7 halogen 9003and H4 bulbs look quite similar on the outside, and in some forums, you'll read that they are the same, while on others that they are different. So, Areall H4 bulbs the same? When to Use H4 Bulbs Since different bulb types have different fittings, they aren’t interchangeable. If your vehicle requires H4 bulbs, you can’t simply switch to another bulb fitting. The only exception is the HB2 or 9003 bulb, which are identical to H4 bulbs. Allof the bulbs discussed in this post - H1, H3, H4, H7, H11, HB3, and HB4 - are in Group 1. These bulbs are primarily used as headlights due to this classification. CarBulb Types. Most headlights hold a cluster of two or three bulbs: the dipped/main beam headlight, the sidelight and, in some cases, the indicator light (many older cars store the indicator light in a separate unit). Meanwhile, most rear light clusters hold the tail light, the reversing light, the fog light and the brake light. Forexample, there are H4 bulbs that have two filaments rather than one, whereas there are H18 units that are smaller but are more powerful and brighter in comparison. The same principle Yes 9003 and H4 bulbs are the same headlight bulb type. The 9003 designation is used in the US, while H4 is more common in Europe, but they share identical dimensions. Introduced in 1971, the H4 was the first halogen bulb with two filaments to Itis not possible to replace a H4 bulb with a H7 one or vice versa as the differences are just two great. There are two main reasons why they aren’t interchangeable: The type of H4 H7, and H11 bulbs are not the same but all belonging to Group 1 lightbulbs per the United Nations’ universal standard for automotive light bulbs. Group 1 means the bulbs can be used for any purpose, but hcLi.