Semi-tempered glass is also called heat-strengthened glass. It is a kind of product between ordinary flat glass and toughened glass. It also has the characteristics of high strength of tempered glass, while avoiding poor flatness of tempered glass, easy to blew, once destroyed, The overall smash and other shortcomings. When the semi-tempered glass breaks down, it radially cracks radially along the crack source. Generally, there is no tangential crack propagation, so after the damage, the entire structure will not collapse. Semi-tempered glass is suitable for curtain walls and outer windows in buildings and can be made into semi-tempered coated glass with better image distortion than tempered glass. However, it should be noted that semi-tempered glass does not fall within the scope of safety glass, because once it is broken down, there are still sharp fragments that can hurt people and cannot be used for sunroofs and occasions in which human body may be impacted.