The large Tesa Clean Air fine dust filter is intended for the ventilation outlet of your laser printer. The printer filter blocks up to 94% fine dust that comes out of the printer. Fine dust particles are so small that you cannot see them with the naked eye. This filter prevents them from getting into the air and from being inhaled on a daily basis. The filter is made of 3-layer fleece, to which fine dust adheres, but on which no mold can grow. The filter can be secured with self-adhesive Velcro that is supplied within the pack.