KF94 is one of the grades given to Korean health masks. ‘KF' stands for ‘Korean Filter'. Korean masks must be certified by the Korea Food & Drug Administration (KFDA) and will be rated KF80/94/99 depending on their performance. The numbers quantify the filter performance of the mask. KF94 blocks more than 94% of the average particle size of 0.4μm It is specifically designed as 3D flat-fold (also referred as fish-shaped) to provide wearer with comfort and more space to breathe. ( Adult Use Only ) When properly used, this product will filter at least 94% of PM2.5 airborne particles to protect the wearer from exposure to harmful air pollutants.