Convenient replace : easy replaceable filters,the product includes one activated carbon masks, two valves and filter cotton, you can replace by yourself .the mesh cover can be washed to keep cleanEasy to replace: the mask can be washed when they get dirty.and you can replace them with another activated carbon masks, valves and filter cotton by yourself (Not included)Best protection: the allergy mask separation of 98% of the dust, chemicals, smoke and particles, it can be used for dust, anti-vehicle exhaust, anti-pollen allergy, pm2.5, for cycling, hiking, skiing and other outdoor activitieSuit for most people : made of elastic material, the size can be adjusted to meet the most head type (up to 27.9 inches). With a fixed aluminum sheet on the bridge of the nose, unigear masks can fit different sizes of face well to prevent sliding. Lightweight, adjustable and smoothableUnique ventilation design, a plurality of holes, excellent permeability, Exhale ,the valve is opened without resistance ,double air breathing valve, air resistance is smaller ,smooth breathing+^+EASY TO REPLACE: The mask can be washed when they get dirty.And you can replace them with another activated carbon masks, valves and filter cotton by yourself(Not included)