That’s right four hundred forty masks (6 cents per). Yes it’s Amazon but this is a good deal.
This is the link: https://www.amazon.com/dp/B08J1THV9G
It is from a sub-company of Amazon that specializes in deals so it is legit-ish. The ones a close friend received came in an official 3M branded box (a huge brown box not retail packaging).
They’re individually packaged in the official sealed wrappers, had lot codes on them and looked to be in good shape. No weird smells either and the elastic and nose pieces seemed fine. No expiration dates unfortunately if that’s super important but the box had a barcode and I suppose you could contact 3M and ask about that lot number.
5 year rating is based on NIOSH and the 3m warranty. During 2020 there was some papers put out by NIOSH regarding using beyond their expiration date (due to shortages) and it’s the usual about watching for straps and cushioning to fail first. No real way to check the electrostatic filter without a proper tester I guess. Idk if the fit test technique would be as useful?