The Bliz Tracker Sunglasses with Bonus Lens gives you an excellent fit and unsurpassed optical clarity when you're skiing big mountain faces, ripping technical singletrack, and paddling across serene lakes. Sporting a slew of innovative features, the Tracker Sunglasses are ideal for outdoor enthusiasts seeking UV protection, fog free clarity, and an ultra secure, highly customizable fit. The unbreakable polycarbonate lens is great for users who aren't exactly nice to their shades, and there's also a bonus lens for swapping during variable light conditions. Conforming to your nose and temples for the best possible fit, the soft, infinitely adjustable nose piece and wire core temples provide total customization. Another major benefit of the adjustable nose piece lies within its ability to enhance airflow during fast paced activities, such as skiing and mountain biking. Simply bend the nose piece to allow for more air passage between the bridge of your nose and the sunglasses. The frame uses near bombproof Grilamid TR 90, ensuring long lasting use, even through the most rigorous activities. What's cool about this frame is the bottom snaps off, allowing you to change its look and reduce weight when necessary. Two removable Jaw Bone bottom pieces are included for customizing the look. Other cool features include a snap in, adjustable strap for added security, as well as a protective case for travel and storage.