Please Note： Usually one filter can be used for 21 days, It is recommended to change at any time during flu and heavy pollution periods Package contents：KN95 Mask + Filter (Filters can be purchased separately). Color:black, grey, orange, blue. Activated Carbon Dustproof Mask Are you now troubled by dust chemicals, smoke and particles, Do you want to enjoy a free outdoor life? Common mask ? It has no effect. Moving purifying respirator? It is large and burden That's a good reason to buy this Activated Carbon Dustproof Mask. Refused to be a human vacuum cleaner, wear a dust proof ,anti-haze mask. A Must Have for outdoor activity Suitable for dust, anti-vehicle exhaust, anti-pollen allergy, PM2.5, for cycling, hiking, skiing and other outdoor activities