McKesson Surgical Mask by McKesson are classic anti-fog masks with ties to hold together. Comfortable, cool, and breathable. ASTM F2100-11 – Level 1 Barrier. Fluid Resistance: ASTM F1862 at 80 mm Hg. BFE in excess of 98%. PFE in excess of 98%. Delta-P: Less than or equal to 2.6. Flammability: Class 1. Single Use. Not made with natural rubber latex.