Docooler&reg; Outdoor Sports Mask Filter Air Pollutant for Bicycle Riding Traveling Open-air Activities Protective Universal Designed with a non-woven cloth?filter to screen out air pollutant like dusts and vehicle fumes. Replaceable and washable filter, and is designed to be effective for at least 3 months in normal daily use. Designed with two one-way valves to allow easier exhalation of heat, water vapour and Carbon Dioxide,suitable for glass wearers. Aluminum lock, help to fit the mask onto nose stably.Made of SBR?to give a comfortable and secure fit.