Although these masks seem not to meet the high filtration standards of the KN95 masks on the site, I still wear them often because they are the most comfortable masks I've found. They fit my face (I suppose your mileage may vary depending on your bone structure) better than any others, the seal seems to be good, they allow movement, and my glasses don't fog up. There's something to be said for a mask that you can actually wear. If I'm really going to be in close confinement with people for a long period of time, I'll bite the bullet and wear a rated high-filtration mask. If I'm just running into a store to buy something or keeping a mask handy in case students stick their heads into my office, this is my go-to.