3-layer surgical mask. Packaging: 50pcs/box For daily use in every day activities. ASTM specifies testing with a droplet size of 3.0 microns containing Staph. Aureus (average size 0.6-0.8 microns). In order to be called a medical/surgical mask, a minimum 95% filtration rate is required. Moderate and high protection masks must have bacterial filtration rates greater than 98%. Particulate Mask N95, KN95 is recommended for day to day activities including walking around, sanding, grinding, sawing, sweeping and insulating. This classic disposable N95, KN95 particulate respirator is designed to help provide comfortable, reliable for day to day users and worker respiratory protection against certain non-oil-based particles.