How to choose hiking sunglasses

On a trail the glasses need to stay put and block light from the sides. A wraparound frame follows the curve of the face and cuts glare from above and to the side. Try them with your head moving: they should not slide when you look down at your feet.

Look for a clear UV rating on any pair you buy, such as "UV400" or "100% UV protection", and check who stands behind the claim. UV exposure increases with altitude and off bright surfaces such as snow and water, so this matters more outdoors than in the city.

Darkness is set by the lens category. Category 3 is the usual choice for bright sun. Very dark category 4 lenses are for extreme glare such as glaciers and are not suitable for driving. Colour changes how the scene looks:

• Grey and silver mirror: neutral colours, general use in bright light.
• Warm red or orange tints: often chosen for added contrast in flatter light.
• Green: tends to keep colours looking natural.
• Purple and blue mirrors: mostly a style choice, worn in bright light.

A mirror coating reflects part of the light before it reaches the eye, which makes lenses look darker from outside and helps cut glare in bright conditions. It also sets the look of the glasses: silver, red, green or purple.

Lighter frames are easier to wear for hours. Resin, nylon and titanium are common frame materials for outdoor eyewear. Titanium is strong for its weight; 3D printed resin can be shaped into vented, open designs that would be hard to mould.

Rinse dust off before wiping, use a microfibre cloth, and keep the glasses in their case in a pack so the lenses do not scratch. STRATOS GLASSES includes a case with every pair.