- Cool Flow exhalation valve. -Good fit of the mask during the period of use. -High and reliable filtration of particles with less exposure of the mask wearer. -Reduces the fogging of the glasses and increases the wearing comfort due to the low exhalation load. -Improved compatibility with glasses / eye protection. -EN 149: 2001 + A1: 2009 Certified: Tested and certified according to European standards.