3M protective mask claims to have a cold flow exhalation valve, why is it called a cold flow exhalation valve?

The 3M cold flow exhalation valve is closed when inhaling, because the air pressure inside the mask is less than that outside the mask, and the valve plate will open when exhaling. The mask with 3M cold flow exhalation valve can reduce the accumulation of heat and moisture inside the mask and make breathing more comfortable. I hope the above reply will satisfy you!

Puweixin meets the highest standards of medical masks in the United States and has good filterability. Tmall has it, which is not only anti-particle but also waterproof. The filtration efficiency is 99.8% for particles as small as 0. 1 micron, and 99.9% for bacteria or virus carriers as small as 0.3 micron (common in droplets). SecureFit patented technology is adopted to adapt to different face shapes and achieve a high degree of fit. At the same time, the six-point support disperses the pressure, and there is no ligature mark on the face, which is very comfortable to wear.