3M 9004 IN - Pack of 10 White Respiratory Mask has the filtering efficiency ranging 80 % when tested against 0.3-micron sodium chloride particles. 3M nose mask is made up of 3 layers of filters — the largest dust particles are filtered out by the external layer. The internal layer of mask preserves the respirator’s shape, and the middle layer constitutes electrostatic filter media. It can be easily folded and placed in the pocket without any hassle. 3M respiratory mask has a cup shape design that comes with an aluminium nose clip. It also has a neoprene elastic band for a secure fit on every type of face. It is a form of disposable face mask for respiratory protection against the fine dust particles. It is not recommended to use the mask in acid/alkaline/gas particles.