COVID-19 KN95 Respirator Face Mask. 4-Layer. Outer Layer, Filter, Non-Woven. Electrostatic Meltbown Layer. KN95 Standard Filter Material, Filter Bacteria. Electrostatic Meltbown Layer, Enhanced Filtering of Dust. 95% Rated Filtration. One Size Fits All. Application Scope and Limitation: Suitable for protecting all kinds of fruit particles such as dust smoke microbes. Not suitable for protecting against harmful gases and steam. Not suitable for hypoxic environments underwater operations escape and firefighting. Not Suitable For Fitting a Baby Size. Tips: If you find the following situations please change mask immediately: dyspnea or discomfort, The mask is died such as blood stains or droplets, the user feels large respiratory resistance, the mask was broken. Storage Period: Three Years.