Every piece of glass, no matter how big it is, must have the 3C mark. This is true tempered glass.

Those that are not marked with the 3c certification mark may not be tempered glass, but semi-tempered or non-tempered glass.

Toughened glass has a self-explosion rate of three thousandths, but the self-explosion of tempered glass generally occurs when the cooling temperature is not controlled well, and generally it will not self-explode after molding. Only hitting the corners of tempered glass can break it.