Although the Chinese KN95 standard is a decent standard, there is no one in the Chinese government or in the United States government that actually tests these masks to make sure that they meet the standard, so you’re at the mercy of the seller (whoever that might be because it’s not listed).
CDC studies have found that up to 60% of KN95 masks are fake; some of those filter worse than pulling up a t-shirt over your face!
For a little more (70 cents a mask compared to 50 cents each for these), you can get guaranteed genuine 3M VFlex N95 masks from Amazon. They will filter better than these, be easier to breathe through, and leak less; so they’ll give you far better protection, be far more comfortable (using headbands rather than earloops), and fit a wider variety of faces. They’re also the best masks I’ve used for singing.
Even if you assume these masks are genuine, the 3M masks are a far better deal.
BE SURE TO BUY FROM A LISTING THAT IS SOLD BY AND SHIPPED FROM AMAZON! 3M masks are often counterfeited, but you’re safe if buying from a known source you can trust (Amazon or other 3M official distributors).
I accidentally deleted my post saying this doesn’t list a manufacturer to look up it’s certifications, but there are great KN95s like Powecom masks. They’ve been tested in the USA and videos of the results are even on YouTube. My mom’s an elderly cancer patient so we’re always looking for great masks. Powecom has kept them safe.