The Stealth sunglasses are one of our most functional sunglasses to date with the advanced FluidFlo® technology cleverly integrated into the sunglasses' design. The lower vents let air inside the sunglasses, offering you some much-needed fresh air, which then exits along with the air flowing in from the top vents. This makes the Stealth an effective go-to option when other sunglasses would fog up in cold or humid conditions. or make the rider fatigued due to limited air circulation. So whether you're on a bike, a run, or in a triathlon, the Stealth is at home in all conditions and you remain fresh and active even after long hours of physical activity.