The New York Times: “Knowing which mask to pick and making sure it’s not a fake requires the sleuthing skills of a forensic investigator. Our guide can help…Unlike cloth masks, high-quality masks — called N95s, KN95s and KF94s — are made with layers of high-tech filtering material that trap at least 94 to 95 percent of the most risky particles. Under a microscope, the filters look like dense forests of tangled fibers that capture even the hardest-to-trap particles that can bounce around and escape the fibers of cloth masks. High-grade masks also have an electrostatically charged filter that helps attract and trap particles…”

See also via CDC – How to tell if your N95 Respirator is NIOSH Approved and infographic – Required Labeling of NIOSH-Approved N95 Filtering Facepiece Respirators