Question: what is the difference between h1 h4 and h7 bulbs?
Answer: Even though these bulbs are in the same category, they're not interchangeable. Whilst an H1 and a H7 bulb may look the same in terms of light output, an H7 bulb won't fit into a socket for an H1 bulb. This means that you must stick to the bulb fitting that your vehicle uses.