There are two main types of sunglasses, one is the "sun visor". In sunlight, people usually adjust the pupil size to adjust the luminous flux. When the light intensity exceeds the eye's ability to adjust, it will cause damage to the human eye. The sunshade mirror can block the sunlight to reduce the fatigue caused by excessive eye adjustment or the damage caused by strong light stimulation. The other type is "light-colored sunglasses", which is also a popular variety in recent years, mainly Decorative effect, can also be used when the sun is not strong. Experts remind that the choice of the color depth of the lens should be determined according to the location of the desired activity. For different light sources and occasions, the color of the lens will affect the shading effect. To make the sunglasses effectively block the summer glare, the color of the glasses should be deep enough, but the rider or driver should not choose too deep lenses.