The full face tempered glass is a full coverage tempered glass protector, specially designed to safeguard your mobile screen from scratches and other damages. In case of dropping the phone, it does not guarantee that the screen won't break along with it, but it provides additional protection.
It does not affect the screen's functionality. The black border covers the entire surface of the screen, including the edges. It has adhesive across the entire surface, unlike edge glue glass protectors which only have adhesive around the perimeter.
This design helps ensure better fit and trouble-free touchscreen operation. Additionally, it prevents dust from passing underneath, which can happen with edge glue products when the perimeter adhesive wears out.