Because it is directly blocked in front of the eyes, the transparency of the PET sheet is very high. Generally, transparency is required to be more than 95%, so as not to affect the line of sight in work and life.
At the same time, the thickness of the PET also has certain requirements. It must have a moderate thickness so that it is not easy to deform and better protect the entire face.
Because the heat generated when speaking in front of the eyes and mouth is blocked, it will generate fog and affect the line of sight, so PET must be anti-fog on both sides to ensure that it is not disturbed by fog during use.