High performance three-tier structure. The first layer of AIRism Mesh fabric is smooth and breathable. The second layer filters out up to 99% of particles. The third layer also uses AIRism mesh fabric for even better breathability and comfort. - The mask has a bacterial filtration efficiency of 99% and pollen particle collection efficiency of 99% (initial values). - Available in four sizes. - Clear size indicator on mask makes it easy to differentiate your mask from others at home. - Washable for multiple uses. - We have found that after repeated washing, the bacterial filtration efficiency and pollen particle collection efficiency, which indicate filter performance, are reduced to 95% and 93% respectively after 20 washes at 40°C.