Mask Loaded With Active Carbon Pre-Filter, Breathe well * Protection Against Airborne Pleated Design. Its Main Characteristics Are As follows: Noxious Gas Defense, Deodorization, Bacterium And Dust Etc. It Can Stop The Dust Smaller Then 5um And many Kinds Of Bacterium Spreading In The Breathing System. it is the Best Choice Of Doctors, Nurses And Patients.