The idea of the sun visor comes from South Korea. The brim of the regular product is made of "patent film for blocking ultraviolet rays" of Mitsubishi Corporation of Japan, which can protect facial skin and eyes. Products are very popular in Korea, Japan and other countries. At present, most of the sun hats popular in the domestic market are copied by private workshops in Zhejiang and other places, and the factory name and address are not marked. Many products are "three noes" and there is no quality guarantee. This kind of sun hat is actually the same as sunglasses. Bad choice will hurt your eyes. Due to the uneven density of plastic, the scenery seen by inferior sun visor may be deformed, which will cause or aggravate people's eye fatigue, affect the refraction of eyes, and then affect people's vision. However, a qualified sun hat will not hurt people's eyes.