The complete guide
HB4 (9006) Headlight Bulbs, A Plain Buyer's Guide
The problem nobody notices until it is dark
Headlight bulbs rarely die with any warning. They fade. A halogen bulb slowly loses output as the filament ages and the inside of the glass darkens, and because this happens over months your eyes keep adjusting along with it. You think the road looks normal. Then one side fails completely, you drive home on a single beam, and suddenly it is obvious that the remaining bulb was not doing much either.
That is the situation this pack is built for. Two HB4 halogen bulbs, 55 watts each, so you can change both sides in one go and stop guessing about whether the other one is nearly finished.
HB4 and 9006 are the same thing
This trips people up constantly, so it is worth saying plainly. HB4 is a fitting code. 9006 is another code for the identical fitting. Some packaging prints one, some prints the other, and plenty of parts catalogues list them together as HB4/9006. If the old bulb you pulled out of your car is marked with either code, this pack is the right shape.
The base has a keyed plastic collar with a specific profile, which means it only drops into an HB4 socket one way round. You cannot force an HB4 bulb into a socket meant for a different fitting, and that is a useful safeguard. It also means there is no adaptor to buy and nothing to modify.
What you are actually getting
The facts on this product are short and we will not pad them out. It is a pack of two halogen bulbs. The fitting is HB4, also written as 9006. Each bulb is rated at 55 watts. The condition is new.
If you have seen listings elsewhere shouting about percentage improvements, treat them with some caution unless the test conditions are published alongside them. The honest version here is a standard halogen replacement with a known fitting and a known wattage.
Likewise, we do not claim an approval marking for these bulbs. If you specifically need a bulb carrying a particular approval mark, look at the marking printed on the bulb you are removing and get in touch with us first. We would rather have that conversation before you order than after.
How to confirm the fitting before you buy
There are two reliable methods and one unreliable one.
The first reliable method is the owner manual. Low beam, high beam, fog, indicators, and so on. Find the lamp you are replacing and read the code.
The second reliable method is the bulb itself. Pull the old bulb out, turn it so you can see the base, and read what is printed there. If it says HB4 or 9006, you are matched. This method is better than the manual in one way, because it tells you what is actually in the car right now rather than what left the factory.
The unreliable method is looking at a photo and deciding it looks similar. Several headlight bulb bases look alike at a glance but have different tab positions. Do not do it that way.
Why pairs make more sense than singles
Imagine two bulbs fitted on the same afternoon. They run for the same number of hours, through the same vibration, in the same weather. When one filament gives up, the other has lived an almost identical life. Most of the time it is not far behind.
Changing both at once solves two problems. It keeps your beams looking consistent, which matters more than people expect, because a strong beam beside a tired one makes the whole picture look uneven on an unlit road. And it saves you repeating the job. On some cars getting to the back of the headlight housing is fiddly, involving a wheel arch liner or a battery that happens to sit right where your hand needs to go. Doing it once is plenty.
This is also why plenty of drivers go looking for the best pair of headlight bulbs rather than a single. Two in the box, one job, done.
Fitting without ruining a new bulb
Most of what goes wrong during a bulb change comes down to two things, heat and fingerprints.
On heat, halogen bulbs run very hot and stay hot after switch off. Turn the lights off, open the bonnet, and give it a few minutes before you touch anything. A hot bulb will burn you and it will mark plastic trim if you rest it down carelessly.
On fingerprints, this is the big one. The glass on a halogen bulb runs at a high temperature, and oil from your skin left on the surface creates a spot that heats differently to the glass around it. That stress is not good for the bulb. So hold the new bulb by the metal base or the plastic collar, not the glass. If you slip and touch it, do not panic, just wipe the glass with a clean lint free cloth and a little methylated spirit, let it dry, then fit it.
The sequence itself is usually straightforward. Disconnect the connector from the back of the bulb. Release whatever holds the bulb in place, which is often a wire clip or a twist collar depending on the housing. Lift the old bulb out. Line the new bulb up with the keyway in the socket, seat it fully, refit the clip or collar, and push the connector back on until it clicks. Switch on and check both sides before you close the bonnet.
Once both are in, have a quick look at the beams against a flat wall or a garage door. You are not doing a proper alignment, just checking nothing looks obviously skewed. If it does, the housing may have shifted and a workshop can set the aim.
Keeping one as a spare
Not everyone wants to change both bulbs today. Fitting one and keeping the second in the boot is a perfectly sensible plan, and it is why a two pack is often bought as the best halogen bulb two pack for a car kit rather than as an immediate pair swap.
If you go that way, leave the spare in its packaging. The packaging keeps the glass clean and stops the bulb rattling against anything metal. Somewhere dry is better than somewhere damp. A glovebox, a padded corner of the boot tool tray, or the pocket in the spare wheel well all work.
Care, in two lines
There is not much to it. Keep the glass clean and untouched, let bulbs cool before handling, and store spares in their box. That is the whole maintenance story for a halogen bulb.
If a new bulb fails early, think back to whether the glass got touched during fitting, and check that the connector was seated properly. Loose or corroded connectors cause more headlight faults than people realise.
The short version
This is a two pack of HB4 halogen headlight bulbs, 55 watts each. HB4 and 9006 are the same fitting. Confirm the code in your owner manual or on the base of the old bulb before ordering, because this replaces an HB4 bulb and nothing else.
When you fit them, let the old bulb cool first, keep your fingers off the glass, and change both sides so your beams match. If you are unsure about the fitting or you need a bulb with a specific approval marking, message us before you order and we will tell you exactly what we know about this product.