Filter Activated Carbon PM 2.5 FM. Do you have problem with dust chemicals, smoke and particles. Do you want to enjoy a free outdoor life? Common Filter? It has no effect. Moving purifying respirator? It is large and burden. That’s a good reason to buy this Filter Activated Carbon PM 2.5 FM. Refused to be a human vacuum cleaner. 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.