Sunglasses are at the same time both practical and decorative. While being fashionable and comfortable, they also protect the eyes against strong sunlight and harmful UV radiation. The CV seal guarantees that the sunglasses block UV radiation.
There are many different types of sunglass lenses. These vary in material as well as color. The green and grey glasses are best at reproducing the colors of the surroundings, while brown glasses are best for driving. Plastic lenses are less scratchproof than glass lenses, but they are lighter and offer better protection against UV radiation.
Sunglasses exist in different filter categories (0-5). A higher category means that more light is blocked. If less light reaches the eyes it becomes harder to differentiate colors, which makes the sunglasses unsuitable for example when driving. Sometimes it is important that the sunglasses cover the eyes completely, to prevent glare in an environment that reflects much light.
Some sunglasses are polarized, which means that the lenses filter out most reflected lights. This reduces glare and makes the sunglasses optimal in environments with snow or water, or when driving. A common misconception is that polarization refers to UV protection.