ASTM Level Additional Details ------------------------------ Product description: Fluid resistant outer layer with a white, extra soft, hypoallergenic cellulose inner layer. These masks are void of all inks, dyes and chemicals and will not lint, tear or shred. Isofluid Plus Earloop Mask - Blue, BFE > 99.8% / PFE = 99.5% at 0.1 micron, Fluid Resistant Spunbond Outer Layer and White Extra Soft Hypoallergenic Cellulose Inner Layer for Sensitive Skin. Secure Loop Ear Loops, Full-Length Aluminium Nosepiece, Latex-Free, Box of 500 masks. ASTM Level 1.