Question: what is the difference between h1 and h3?
Answer: The H1 bulb uses a P14. 5 base, whilst the H3 bulb uses a PK22s base and has a wire protruding from the bottom. ... Your dipped beam and high beam will need one specific fitting of bulb and only one bulb can fit. You can't simply switch H1 for H3 and you can't plug a H1 bulb into a H3 fitting.