Tips for preventing fogging in winter: About the anti-fog, all of our goggles lenses are covered by an anti-fog coating. With proper maintenance, you can help the coating work longer. 1. Always remember to moist the lens inside so the coating can work. 2. Never wipe the lens. 3. After your swim, wash the lens with fresh water and then let it air dry. 4. If the product fog up again, please buy an anti-fog solution or try to use baby shampoo and water mixed liquid. We have customers said this method can work like a charm. Please note that goggles tend to fog up more easily in winter. The fog might be the result of the temperature difference between cold air outside the pool and constant temperature pool water. #1 Top rated Aegend swim goggles easy care and maintenance: -To clean goggles: always rinse completely under cold water to remove chlorine, salt, sand and other contaminants and allow to air dry in a warm, clean environment. -Do not leave your goggles out under direct sunlight as this can dry the soft silicone seals and fade its color. -Never rub or wipe the insides of your lenses as this can scratch or remove the anti-fog coating. -Protect your swimming goggles by storing them in their protective case (included). Caution: Customers who are allergic to silicone please don't buy this product.