I recently bought an older MB that needed a fairly DEEP paint job to remove some heavy scratches and swirls. But of course I didn't want to risk it too deeply, because of the transparent layer. So I bought this gauge and measured the thickness of wherever I wanted to mix. I also measured the thickness in the door opening and trunk lid (where the clear coat is very thin) to see how far I can go. The work turned out very well (almost perfect) and I still had enough clear coat left for the optics and UV protection. I've applied a ceramic coating afterwards for more protection and it looks great. In any case, I found this gauge to be accurate (based on the paint thickness samples provided), easy to use, and reasonably priced compared to similar products.