Being on the face of it should be the opposite of surgical masks, the color is relatively shallow side, in addition, pay attention to part with metal bars should be above the masks, do not wear backwards
Right to the face should be the opposite side of the medical mask, that is, the color is lighter side, in addition, pay attention to the metal bar with the part should be above the mask, do not wear the reverse
The one facing the face should be the reverse side of the medical mask, that is, the lighter side. In addition, pay attention to that the part with metal strip should be on the top of the mask instead of wearing the reverse side