What's the main use of gradient tinted sunglasses?

[Rio Hondo]

I have seen some gradient tinted sunglasses, and I wanna know the purpose of them. Are they only for style or something else?

[Rio Linda]

Gradient tinted sunglasses can not only give the wearers a stronger protection from the sun but also allow the wearers to see more clearly in a darker environment. If there is a strong and direct light from the sun, he can see the top portion of the lens with the darkest color. In the meanwhile, he can still see clearly through the bottom, clear portion of the lens. So this kind of sunglasses are not only for style but also give protection to the wearers.

[Rio Lucio]

Gradient tinted sunglasses are used for different purposes, ranging from pure fashion enjoyment to outdoor sports. A fashion tint usually blocks 10-20% of sunlight. Outdoor activities and daytime driving require related lens tints to have an intensity ranging from 70-80%. 90% tints are suitable for sports like climbing and snow skiing.