The full face tempered glass of Nillkin 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 is compatible with Poco F4.