Changing your filter regularly means peak year-round performance for your air purifier - and your lungs. We're making it as easy and affordable as possible with the biggest filter sale we've ever had. If you're a "buy them as you need them" type, save 5% on all single filters. Want to stock up for the whole year? Filter bundles are up to 40% off. And remember, we are always tax-free & ship for free, too!