Thesimilarities between 9003 and H4. 9003 bulbs are physically identical to the H4 bulbs. When placed side-by-side with no labels, you will not be able to tell the difference between H4, HB2, and 9003 bulbs. They are all dual-beam bulbs with double filaments and are used in many vehicles on the road. The similarities between H4 and
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. Likemany automotive parts in use throughout the world, headlight globes are sometimes referred to by other names. These may include headlight or headlamp bulbs, Halogen globes, HID globes and LED globes. And while the terms headlight and headlamp, and globe and bulb are interchangeable, the type of globe used is generally specific to