Fellowes DX Hepa Filter 9287001. Catches 99.7% of all airborne particles. Catches impurities up to 0.3 microns. Perfect for people who suffer from respiratory problems. Helps prevent the spread of disease. Filter needs replacing every 12 months.Filtering out dust, pollen, mould spores, cigarette smoke and a whole range of other undesirable airborne particles, Fellowes HEPA AeraMax Filters are perfect for ensuring quality air.Stopping 99.7% of all particles and catching impurities as small as 0.3 microns, you have a more reliable way of preventing disease. Perfect for people that are suffering from respiratory diseases such as asthma and bronchitis.