Sunglasses categories

Sunglasses lenses are divided according to their tint level into 5 categories:

Category 0 – suitable for use in cloudy weather (light transmission 80–100%)
Category 1 – suitable for use in partly cloudy weather (light transmission 43–80%)
Category 2 – suitable for use in sunny weather (light transmission 18–43%)
Category 3 – suitable for daily use in strong sunlight, as well as in the mountains or on the water (light transmission 8–18%)
Category 4 – suitable for use in extreme conditions in high mountains or on the water with intense sun; not recommended for driving (light transmission 3–8%).

The sunglasses or the accompanying certificate may also indicate the lens type or filter:

N – stands for a normal sun lens (plastic or mineral glass).
P – is a polarizing lens, meaning it blocks UV rays at a 90-degree angle; suitable for use on the water (plastic or mineral glass).
F – is a photochromic lens that darkens automatically when exposed to UV radiation (plastic or mineral glass). When UV radiation stops, the lens returns to its original color. The category number for photochromic lenses indicates the category in its darkest state, while in its clear state it belongs to category 1.

Most sunglasses have the category of the specific lenses printed on the temple. The corresponding number and often the letter indicating the lens type are shown. So, if the sunglasses or certificate have the mark 3N, it means they are category 3 sunglasses with a normal sun lens.

All sunglasses sold by LensExpress (Ray-Ban, Polaroid, INVU, CentroStyle) provide 100% protection against harmful UVA and UVB rays.