Frequency - made to work with both no headwear, and with different kinds of helmets. They offer a wide, panoramic view. The visible light transfer offered by the photochromic Light Amplifier lens varies between 17% and 75%, thus offering protection between cat1 and cat3. It is the lightest of three available photochromic lenses by Julbo. - Reactiv Light Amplifier cat1 ... cat3 lens - Frame size suitable for most adults - Controlled ventilation in the upper part of the lens - Grip Tech temple material offers a solid hold, without sticking to your hair - Soft nose pad - Lens height 49 mm, width 130 mm - Base 5 - Bridge 13 mm - Temple 123 mm The image displaying the measurements shows a different lens colour. Other images display the correct colour. 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.