This is an inner sheet for masks. It is recommended for those who want to use a mask cleanly all day long, and for those who are concerned about stuffiness and rashes caused by chemical fiber masks. Oxygen-based bleaching is used for bleaching cotton. Since the components of oxygen-based bleach are substances that originally exist in nature, they have an overwhelmingly low environmental impact and are safe for the human body compared to chlorine bleach. * The mask itself is not included in the product, so please prepare it separately. * It cannot be used for the purpose of filtering to prevent viruses.