Packing: This mask filter have 10pcs packing,20pcs packing,30pcs packing and 50pcs packing, PM2.5 protective 5 Layers replacements.filters size: 12 x 8 cm/ 4.7 x 3.1 inches. Five layers protection: Dust mask the first layer blocks larger particles;The second layer is activated carbon filter layer, ;The third and fourth layers can filter 0.03 micron particles.The fifth layer is the inner layer of non-woven,soft and comfortable for your skin touch. Use for: This filter is suiting for training mask, sport mask, air filter face mask, construction dust mask,workout mask, and mask filter with high-grade non-woven fabric,activated carbon,filter cotton,the face mask filters out 98-percent of exhaust,pollen,smoke,dust,chemicals,particles so on. Notice: This link only filter supply, if you need buy dust mask, please visit our shop. After Service:Customer satisfy is our eternal pursue. If you have any problems with our product, please feel free to contact us, we will fix any of the problems in 24 hours.