KN95 masks are regulated by the Chinese government under regulation GB2626-2006 and are rated to filter 95% of particles. In April of 2020, in order to help expand the availability of general use face masks for the general public and particulate filtering facepiece respirators for healthcare professionals during the COVID-19 pandemic, the FDA issued guidance authorizing the use of KN95 masks as suitable NIOSH alternatives under certain emergency circumstances (Source:FDA https://www.fda.gov/medical-devices/personal-protective-equipment-infection-control/faqs-shortages-surgical-masks-and-gowns and FDA https://www.fda.gov/media/136449/download).
On May 7th of 2020, the FDA updated the April guidance and issued further guidance limiting the use of certain KN95 masks as suitable NIOSH alternatives in a healthcare setting (Source: FDA https://www.fda.gov/media/136664/download). EMC Industrial only carries KN95 masks approved by the FDA.