These lenses are transition or light adaptive and change colour in response to UV light levels.
These lenses are designed to reduce glare.
VISIBLE LIGHT TRANSMISSION (VLT)
Categories 0 to 4 in percentage of visible light transmission
Category 0 = 80 to 100%VLT - generally safety glasses that are clear or with a very light tint.
Category 1 = 49 to 79%VLT - casual use cosmetic and fashion eyewear
Category 2 = 18 to 45%VLT - general level of sunglass lens with good UV & visible light protection
Category 3 = 8 to 17%VLT - high UV & visible light protection but may not be suitable for riding on dull days.
Category 4 = 3 to 8%VLT - special purpose sunglasses for extreme glare situations eg snow or water