The Piuma design is a result of our experience in manufacturing the X-Light glasses with the interchangeable lenses. The outcome is a pair of sunglasses weighing just 17 grams. The interchangeable lenses allows you to change to a clear lens on overcast days or low light conditions but still have the protection of the glasses. The lens has been designed to have small ventilation slits at the top to help avoid the lens from fogging up. There are two LA PIUMA models: I and II. The difference between the two is the cut of the lens.