There are a couple of main issues: 1) is that some bulbs can be inserted into the holder two orientations, but only one is correct as there is often a shield s

There are a couple of main issues: 1) is that some bulbs can be inserted into the holder two orientations, but only one is correct as there is often a shield stopping light bleeding up. 2) is that some lights appear to be almost horizontal rather than aimed down, if you're driving a smaller car you have lights almost aimed right at you - we need to tax cars based on size as well as emissions.