A category 1 to 3 photochromatic lens works in many conditions: at its brightest, the lens transmits 75% of light, and at its darkest, the glare protection is at a level suitable for sunny summer days. Julbo cycling glasses are designed to work very well with cycling helmet straps. - Lenses made of Trivex plastic have a light transmission of 17 - 75%, cat1 ... cat3 - The lenses only react to lighting, not to temperature like many cheaper ones - There is an anti-fog treatment inside the lens - Air Link frame help the glasses stay well away thanks to the elastomeric material - Grip Tech coating at the ends - Very wide field of view thanks to Panoramic View design - Ventilation holes between lens and frame Julbo has been making sunglasses for more than 135 years. By buying Julbo, you are investing in a quality product and can rest assured the glasses offer perfect UV protection.