The tempered glass is a hardened glass, specially designed to cover and protect your phone's screen from scratches and other damage. It does not affect the screen's functionality. In case of a phone drop, it does not guarantee that the screen will not break along with it, however, it is an additional protection. It has adhesive over its entire surface, unlike edge glue glasses that have adhesive only on their perimeter. This helps in better application and seamless touch screen functionality. It also does not allow dust to pass underneath, which can happen with edge glue when the perimeter adhesive wears off. It is compatible with Galaxy M20.