I bought these as an experiment on this website, because it was so cheap. Around $40 for 50 masks by 3M. Ha! What a joke! Can't the Chinese even hire someone to do spell checks? I mean, they can even just use Google translate. The packaging had misspelled words everywhere. The mask felt paper thin. I did the flame test as shown on YouTube to melt the middle fabric. Well, it almost started a fire in my house. FAKE MASKS. Beware. Definitely not 3M. I wish I can leave zero stars.