Added sorbent layer helps to filter nuisance levels of acid gas irritants (less than OSHA PEL). Exhale valve reduces hot air build-up to keep workers cooler. Dura-Mesh® shell resists collapsing even in hot, humid work environments. Contour-molded nosebridge with soft foam nose cushion provides all-day comfort. Softspun® lining increases comfort and durability. NIOSH certified to have a filter efficiency of 95% or greater against particulates free of oil. Meets heat and flame resistance in accordance with ANSI/ISEA 110-2003, Section 7.11.1.