Back tempered glass is a type of screen protector designed to protect the back of a phone from scratches and damage. It is made of tempered glass, which is stronger and more durable than regular glass. The tempered glass is typically 0.3mm thick and has a 9H hardness rating, making it resistant to scratches and shattering. Some features of back tempered glass include: Ultra HD clarity and smooth touch Anti-fingerprint and anti-scratch coating Case-friendly design to fit most phone cases Easy installation and bubble-free application Water-resistant and oil-resistant