Sunglasses

it is indicated by a number from 0 to 4 and has nothing to do with price. Lower categories are sufficient for the city and everyday wear, while higher ones belong in the high mountains and above snow, as the reflection from snow multiplies the radiation. Dark lenses without a proper filter are worse than no glasses at all: your pupils dilate in them and let in more radiation. Polarisation reduces glare from water and wet roads, but it can make reading the terrain harder on snow. For high mountains, look for side shields as well.