Anti-Pollution Mask.The 3M 9004GV In Is Composed Of Three Layers Of Filters. The Outermost Layer Filters Out The Largest Dust Particles, The Innermost Layer Preserves The Respirator S Shape And The Middle Layer Is Composed Of Electrostatic Filter Media. Grey Colour of the mask does not allow the mask to get dirty easily outdoors. These 3 Layers helps in Purifying the polluted air by upto 95%. The cool flow Valve makes it more comfortable while using it for long hours and warm/hot conditions.