KN95, KF94, N95, 3M ... What do these terms mean?

Q: KN95, KF94, N95, 3M ... What do these terms mean?
A: N95 is U.S. certification standards; KN Chinese certification standards KN95 in 95 i.e. the filter at least 95% of the non-oily particles;
KF94 of KF Korean certification standards, 94 i.e. the filter at least 94% of the non-oily particles;
so The protection level of KN95 is greater than that of KF94.
3M is the world's largest manufacturer of masks.