sold at The Board Basement allow you to change the lenses depending on the weather conditions.
The most common types are:
Clear Lenses - Good for low visability conditions such as Night time or in snow domes where there's good light, but it's not reflecting too brightly.
Yellow or light tinted lenses - Great for when it's really dumping down the snow or whiteout days. They enhance the contrast, making details easier to pick out.
Bronze or Mid-Tinted lenses - The most versatile lense that is a good all rounder, blocking out enough light for sunny days, but not so much that you wont be able to see if clouds roll in.
Mirror lens - Suitable for the really bright days. The Mirrored lens reflect most of the light, protecting your eyes.
Find the lens tint you need by adjusting the VLT index (Visual Light Transmittance) slide.