The full face tempered glass is a full coverage hardened glass specially designed to protect your mobile phone's screen from scratches and other damages. In case of a fall, it provides additional protection, although it does not guarantee that the screen won't break along with it. It does not affect the functionality of the display.
The black frame covers the entire surface of the screen, including the edges. It features adhesive across the entire surface, unlike edge glue screen protectors which only have adhesive around the perimeter. This helps ensure a better fit and preserves the touchscreen's functionality. It also prevents dust from getting underneath, which can happen with edge glue protectors when the perimeter adhesive wears out.
It can be removed at any time without leaving marks or causing problems to the screen.