A windscreen or the mobile car window repair glass in the front of your vehicle or vehicle is not made up of a single sheet of manufactured glass. It's really 2 layers of glass that are separated by a complete layer of polyvinyl butyrate. This layer of PVB essentially glues and also seals both items of glass together. This offers several functions, though the most important is to preserve the integrity of the windscreen. In the event of damages, the windscreen is less likely to shatter.