Thanks!

Yes we are adding those notes now... most of the KN95 fails are the incorrect markings on the mask. To pass the GB2626-2019 standard (where the KN95 lives) you have to put the manufacture name, standard name (eg, "GB2626-2019"), and mask type (eg, "KN95"). About 90% of "KN95s" on amazon are fake because they do not include this... I image because the manufacturers are just trying to make a quick buck and didn't ever read the 57 page standard.

If a KF94 fails it is usually because it's not made in South Korea where all official KF94s are made.