Everybody knows that sunglasses are must-have items in summer. However, there are so many types of sunglasses products. How should we choose the right sunglasses when buying? The following are the most important points to note:
1. Look at the transmittance.
Transmittance (projection coefficient): the transmittance or penetration of visible light, that is, the degree of light transmittance. The lower the transmittance, the lower the degree of light transmission, and the more difficult to see clearly. For example, the transmittance of the sunglasses lens is 40%, which means that only 40% of the visible light can pass through the lens into the eyes.
2. The sunglasses categories on the tag
Category 1 light-tinted sunglasses, with a transmittance of 43%-80%, features the lightest color, which means the least sunshade and light transmittance reduction. They aremostly used for fashion accessories;
Category 2 sunshades have the transmittance of 18%-43%, and also slightly tinted light colors, which are more suitable for cloudy or overcast days;
Category 3 sunglasses adopt lenses with a transmittance of 8%-18%. Most sunglasses belong to this level, which are ideal for outdoor activities like the beach outing and mountaineering.
Category 4 sunglasses are designed for special-purpose with a transmittance of 3%-8%. They fit for skiing, deserts, welding and other extreme environments;
It must be emphasized here that the transmittance must be greater than 8% according to driving requirements!Therefore, it is not recommended to wear the fourth category of sunglasses when driving. Driving with sunglasses with unqualified transmittance may make it difficult or impossible to identify traffic lights, and it is very easy to cause traffic accidents. Jefoo sunglasses belong to category 3 with a proper a transmittance of 8%-18% and ideal for driving.
3. Check the UV protection label
Sunglasses with UV protection generally have the following marks:
UV400: The average transmittance of UV rays with a wavelength below 400nm through the lens is no more than 2%;
UV380: The average transmittance of UV rays with a wavelength below 380nm through the lens is no more than 2%;
Nearly 100% UV absorption: It means that the lens can almost 100% filter out UV rays in all wavelength ranges, and the average transmittance is no more than 0.5%.
Therefore, if the sunglasses you like have the above features, don't hesitate to buy them.
