Size: The Active Mask of Banale, Made in Italy company on the market since 2015, is a washable mask that protects from dust, pollen, smog and bacteria thanks to its innovative filtering technology. Furthermore, its breathable properties make it suitable for outdoor sports. Active Mask is a comfortable and effective protection to move outside the house. In fact it has been studied and built with quality materials that make it fresh and comfortable. The filtering heart is made of PU (polyurethane foam) much more powerful than a surgical mask or a cotton mask. Another fundamental aspect is that it is washable (even every day in hot water) as a head of linen and therefore reusable . Finally it is practical because foldable and therefore easy to store. How to choose the size: measure the distance between the back center of the ear and half of the nose. Between 12 and 14 cm the size to choose is Kids, between 14 and 17.5 cm is Medium, greater than 17.5 cm is large.