If I could give this six stars I would. I purchased because of the good reviews and the relatively low price. My headlights were not in that bad of shape, but I wanted to improve their overall clarity, and this product absolutely delivered. With very little effort, my headlights looked brand new! My friend and I, both of whom have used more expensive, labor-intensive, and time-consuming products in the past, were blown away. Not only was this product easy to use, but both of us thought the result was better than the aforementioned headlight restoration kits we had used in the past. We were so impressed we ended up cleaning the headlights on three different vehicles, and each time walked away extremely pleased with the result. Is the effect permanent? I don't know, nor do I care. If the headlights fog up again in a couple of months, three minutes will be all it will take to get them shining again! I followed the M17 up with the M10 polish, as directed. Do yourself a favor and buy this product.