What is the difference between pfe and bfe

The inner S layer is ordinary non-woven fabric, mainly for moisture absorption;

The outer S layer is a non-woven fabric with a waterproof treatment, which is mainly used to isolate the liquid sprayed by the patient, which has the effect of preventing spray;

The middle M layer is made of electret-treated melt-blown non-woven fabric, which can filter bacterial suspended particles and is the most important core layer.

Meltblown cloth, commonly known as the "heart" of the mask. Its main raw material is polypropylene, which is a film composed of many criss-cross fibers stacked in random directions. The fiber diameter ranges from 0.5 to 10 microns, and the fiber diameter is about one-third of the hair diameter.