The full face tempered glass is a full coverage hardened glass, specially designed to protect your phone's screen from scratches and other damage. 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 does not affect the screen's functionality. The black frame covers the entire surface of the screen, even the edges. 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 M31.