Light source is great without any noise like other cheap ones.
The fiber optics are just likes fish lines in different sizes.
I got three sizes but the .03mm bundle is some how mixed with a few .07mm.
These lines specifically the big size will leave noticeable mark on the headliner, the small size will be less but you will see the traces they leave on the headliner when not turn on. My headliner is black and i see a lot. And it is also depending on the headliner material too.
Overall is is great product and one of the best DIY project.