VLTVLT or visible light transmission is the light that passes through the lens to reach your eye. For example, a dark tinted lens will have a low percentage of VLT, while a light tinted lens will have a higher percentage of VLT.FILTER CATEGORIESCategory 0Light transmission 80-100% • Clear or very light tint. Typically sports or protective glasses designed to guard against wind, dust, or debris, but not against the sun.Category 1Light transmission 43 - 80% • Very lightly tinted lenses, usually yellow or orange, suitable for lower sunlight conditions or protection against wind or dust.Category 2Light transmission 18 - 43% • Medium dark filter suitable for moderate sunlight and casual wear. Their tint is slightly lighter than usual. Can be used for spring and autumn walks on sunny days. They will also be useful for driving and moving frequently between shade and sunlight.Category 3Light transmission 8 - 18% • Dark filter suitable for intense sunlight on the beach or in the city.......