This mask filter removes very fine particles and nanoparticles (50 nanometers) that can cause serious health problems. At the same time, its filtering effect also exceeds the similar products under the European standard. An exhaust valve is also provided on the outside of the mask to send out the exhaled gas of the athlete at the first time. In terms of wearing, first of all it is very light, reducing the burden on the athletes. Secondly, it consists of two fixed straps, one on the top of the head and one on the neck. Perhaps the comfort level varies from person to person, but the stability should be enough. of.