I'm changing my left headlight bulb and it says it is a H7U one. What does the U marks?
I searched a bit and found two possible solutions:
- Marks the shape of the bulb.
- The bulb is not ultra violet sensitive, therefore it is suitable for use in Parabollic Plastic Reflectors.
I saw the first one mentioned on multiple sites, the second one was told by this guy:
H7U means the bulb is NOT ultra violet sensitive, therefore it is suitable for use in Parabollic Plastic Reflectors as fitted to the later Astra's Ordinary H7 halogen bulbs can cause yellowing to some plastic reflectors as experienced in Ford Mondeos
What is the truth? Does it really indicates shape? What does the shape influence then? Why would there be different type of shapes?