Additional Details ------------------------------ Product description: You should replace the filter on your Salin Device every 4 to 6 months to maintain its effectiveness. The Salin salt cartridge also includes a G4 Pre Filter that removes 98% of airborne pollutants (at least 10 micron in size), including bacteria, mold spores and pollen. To ensure optimal performance of the Salin Salt Therapy Device, the salt filter cartridge should be replaced every four to six months. The therapeutic effect of the device will be compromised if filters are not replaced as recommended. The Salin salt filter cartridge has a shelf life of two years; if not in use please store in a cool, dry place in its original packaging.