The S9 self-priming respirator is a reusable face mask designed to KN95 standards. This means that it will block > 95% of all particulate matter in the air larger than 2 �¼m in size. The mask employs inexpensive replaceable filters. Breathe comfortably with full protection Minimize cross contamination with plastic shield Fits snugly on the face with silicone construction Effective filter with four (4) layers One time fit (No need to continually adjust for comfort) Environmentally friendly because it is reusable Personalize individual masks by attaching identification to it directly