Ordinary N95 masks are not suitable for long time wearing, because N95 masks have poor breathability, and you will feel breathing difficulties when wearing them for a long time. Breathing valve is to improve the breathing difficulty of N95 mask. The breathing valve closes during inhalation and opens during exhalation. A mask with a breathing valve is more comfortable because breathing and inhalation will be smoother. (N95 is not breathable and carbon dioxide is present in traditional masks)

This is a breathing valve, a one-way open valve. When inhaling, it will close; when exhaling, the internal pressure of the mask is greater than the external pressure of the mask, and the valve piece can open automatically. It helps to reduce exhalation resistance, discharge water and heat, and improve the comfort of wearing the mask.