HandyStrap with buckle allows mask to hang around neck when not in use. Ventex valve lets the hot air out faster so workers breathe easier and use fewer masks. Soft foam full flange eliminates pressure points for added comfort. Dura-Mesh shell resists collapsing in heat and humidity. Flame retardants are added to the shell to help decrease flammability. Softspun lining for increased comfort and durability. NIOSH certified to have a filter efficiency of 99.97% or greater against particulate aerosols free of oil. Applications: In environments where an OSHA substance specific standard applies (lead, cadmium, arsenic, MDA) as well as pharmaceutical manufacturing, battery manufacturing, welding, cutting and metal pouring. May be considered for hantavirus; consult with your local health department first. No oils present. 5 Masks per box.