Self-Gard Pro Activated Carbon 4-ply mask has 4 layers Outer layer Spun bond non woven(25GSM), 2nd layer Anti-Microbial activated carbon filter (35GSM), 3rd Layer Melt-Blown filter (60GSM), 4th Layer Spun bonded nonwoven (25GSM). The total GSM is 145. It helps with protection against. Bacteria & Viruses, Pollutants & Allergens, Dust, Pollen, Smoke particles and odour.