Repel 4-ply fluid resistance mask series comes with our innovative HydroGuard layer that provides superior fluid resistance. Latex and fiberglass free, while its inner layer is dye-free, chemical-free, and lint-free. Quad-Fold design provides 15% more breathing volume while the revolutionary CoolSilk lint-free inner layer offers a cool and long-lasting soft feeling without fluffy irritation. ASTM Level 3.