Many people today are looking for improved lighting output from their car's stock halogen projector headlights. However, if you're not an experienced "retro-fitter " it becomes difficult to navigate at times. Take an H7 bulb for example. You've determined that the bulb needed for your car is an H7, but then you realize that said bulb comes in both H7A and H7B. HELP!!!
So What's the Difference?
Halogen H7 bulbs have a metal base with an alignment tab on one part of the base. The H7 HID bulbs have this same alignment tab. H7 HID bulbs also have a return wire that goes along the outside of the glass capsule.
As you can see from the image below, the H7 bulbs have the return wire either directly opposite the alignment tab (H7A) or on the same side as the alignment tab (H7B).
Why Should I Care?
If you use the wrong bulb, the return wire on the HID bulb will be at the top once installed in the headlight. The return wire will cast a shadow down the middle of the car's light output, causing the reduced performance of the light. It's not the end of the world, but you won't be getting the best light output possible.
How Do I Determine What I Need?
The answer is simple. You need to look at the back of one of your headlights (though this is easier said than done sometimes). Note the orientation of the alignment tab for the stock halogen bulb. If it's at the top (12 o'clock position), order an H7A. If it's at the bottom (6 o'clock), order an H7B. If the alignment tab is off to one side, order the style that will place the return wire as close to the 6 o'clock position as possible.
Still Need Help?
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