Features the Dura-Mesh shell which protects the filter media so that it stays cleaner-looking longer. Shell resists collapsing, even in heat and humidity. Softspun lining gives added comfort and durability. Contour molded nose bridge with a soft foam nose cushion provides the wearer an easy comfortable fit. The 2300N95 Series features an exhale valve and is suitable for most welding applications. The exhale valve reduces hot air buildup, reducing breathing resistance and keeping workers cooler longer. The 2400N95 Series has an added carbon layer to help filter out nuisance levels of ozone and organic vapors (less than OSHA PEL). Suitable for most welding applications and fits easily under welding hoods. Theres no metal noseband to adjust and the seal is maintained without pressure points. Straps are securely attached so that they dont break at the seal. All meet heat and flame resistance in accordance with ANSI/ISEA 110-2003 Section 7.11.1.