Conforms to American NlOSH 42 CFR Part 84 standard as N95 class, with filtration 95% effective against particulate aerosols free of oils. NIOSH Approval number TC-84A-4274. Low breathing resistance for increased wearer comfort. Fringe seal avoids open layer around the edges.With collapse resistant double shell construction made to withstand hot and humid conditions. Latex-free synthetic rubber head straps, adjustable nose clip and soft foam nosepiece for comfortable custom fit. Exhalation valve reduces hot air buildup and easy breath in hot/humid environments. All packed 20/box, 6bx/cs.