You don’t need to replace the medifilter every year. An indicator on your Defender device will tell you when you need to replace the medifilter. If there is smoking in the room where the Defender is located, you will need to replace the filter annually, depending on the use and amount of nicotine. In the presence of pets (e.g. cats & dogs), the filter will need to be replaced more quickly.
Filters for the Defender 4000 series are not compatible with the 3000 series. Verify your filters when ordering by using the product number at the bottom of your device. The original medifilter (cartridge) for the FilterQueen Defender 4000 removes pollutant particles, microbes, pollen, viruses, bacteria, allergens and harmful gases from the air with an efficiency of 99.99 % or 0.1 micron.