Molded from elastomeric rubber provides comfort and durability. Low maintenance/Limited use 400 series can be used up to 30 times. Fit over 99.9% of wearers.. suitable for Oil & Non Oil Based Particulate Aerosols including Silica Dust, Lead Dust and Fumes, Break Dust, Exotic Welding, Glass Fibers, Asbestos(Note: specific limitations apply for asbestos removal, see OSHA 1910.1001) andNuisance Levels of Organic Vapors below the Permissible Exposure Levels (PEL) in Ziplock Bag