The disposable PM 2.5 mask filters are made up of five layers, making use of carbon filter technology for more comprehensive protection against particulates, allergens, and pollutants. Each filter has an activated carbon fiber layer centered between two melt blown cotton layers and enclosed by a layer of non-woven fabrics on each side to provide the best filtration to help you breathe easier when outside of the home. Available in a pack of 50, they’re a perfect fit within the built-in pocket of our kid-sized protective masks. Filters should be safely disposed of after each use.