ASTM Level 3 Medical Certified PFE exceeds 99% 4-ply, 4-fold Level 3 Extra soft and comfortable High breathability Fluid resistant Latex and fiberglass free Bonus Chin Strip IMPORTANT: The filtration efficiency and protective ability of a face mask is compromised when the mask becomes wet, torn or dislodged. In general, the higher protection value of a mask the longer it will maintain filtration; however, there is no set rule for how long a mask should be worn as it depends on humidity levels, respiration rate, nasal discharge, talking, etc.