The layered coating on this Giro lens works to increase contrast and provide the wearer with greater depth perception in low light. This lens has a VLT percentage of 50-60%, meaning cloudy days are it's best friend. VLT stands for visible light transmission and refers to the amount of visible light that can pass through an optical lens. The reason this goggle lens has a range for its VLT percentage, as opposed to a single number, is due to the differences between the spherical and cylindrical versions it is manufactured in. Typically, cylindrical lens have a slightly lower percentage than a similar spherical lens.