Contains 1x HEPA-13 and 1x activated charcoal replacement filters compatible with Airthings Renew air purifier. Each offers 4000 hours of cleaning time for an average of 6 months of clean, healthy air. Your Renew air purifier alerts you when it's time for a filter change and the Replacement Filter Pack contains all you need. No special tools are needed to remove the used filters and put the new ones in - it's a breeze!