The full face tempered glass is a hardened glass that covers the entire screen, specially made to protect the screen of your mobile phone from scratches and other damages. In case of a drop, it does not guarantee that the screen will not break along with it, however, it provides an additional protection. It does not affect the functionality of the screen. The black outline covers the entire surface of the screen, including the edges. It has adhesive on its entire surface, unlike edge glue protectors that only have adhesive on their perimeter. This helps in better application and smooth operation of the touch screen. It also prevents dust from passing underneath, which can happen with edge glue when the perimeter adhesive wears off. It is compatible with Xiaomi Redmi A3 4G.