Disposable medical mask
The masks we buy usually have a single sealed package and a stack of several plastic packages. There is no difference between these two types, depending on the amount you use. They are packaged after sterilization. As long as they are made by regular manufacturers, have clear production information, and meet the use standards, they are all compliant.
Some of the most common disposable medical masks have the same front and back materials, and some have front and back sides. The front material will look thicker, and it will also prevent some liquid splashing. It is more durable. The middle layer counts as a filter element, and the surface layer is softer. The general way of distinguishing is to look at the side of the hanging ear rope, the side with the hanging ear rope is the one that fits the face