When choosing sunglasses, you may encounter a parameter marked as: Darkening filter category .
The darkening filter category determines the degree of darkening of the lens of a given glasses model. In the case of Polaroid sunglasses, we can find glasses with the following categories:
Cat. 0 – clear or very light tint - (transmits 80-100% of light)
The lens is completely transparent or slightly smoked. This lens can be found most often as the second or third lens in sports glasses. It is perfect for cyclists during evening riding.
Cat. 1 – light tint - (transmits 43-80% of light)
The juices are slightly darkened - often yellow or amber. They work well in poorer light conditions.
Cat. 2 – medium - (transmits 18-43% of light)
Medium darkening lenses work well on days with low sunlight intensity
Cat. 3 – dar k - (transmits 8-18% of light)
The most common obfuscation filter category. The most universal, perfect for everyday use on sunny days and during holidays in hot countries.
Cat. 4 – very dark - (3-8% of light transmits)
Lenses with very strong darkening. Polaroid does not recommend them for driving due to the very strong darkness. They are used in very bright sunlight, e.g. by mountaineers in snow-covered mountains.
In Polaroid sunglasses, the filter category is marked on the inside of the temple as Filter Cat on each model.
For example: Filter Cat.3 means obfuscation filter category 3 - i.e. Dark
The shading filter category does not affect UV protective filters or polarizing filters. These are completely separate filters. Polaroid glasses with categories, e.g. 3 and 4, provide exactly the same protection against harmful UV radiation and have exactly the same polarizing filter.
The best choice for everyday use and for vacations are lenses with category 3 - allowing 8 to 18% of light to pass through. These lenses are basically used in 95% of Polaroid glasses.
Sunglasses with filter categories 1 and 2 are occasionally found. These are glasses with clear lenses, most often yellow or orange. These lenses