Eco Four Twenty Personal Air Filter Replacement Filters - Set of 2 SET OF TWO: In 1 Eco-Friendly Box, You Get 2 Official Replacement Filters for the Eco Four Twenty Personal Air Filter LONG LASTING: Lasts Up to 500 Exhales Before Needing to Be Replaced. The Average User will use this for 2-3 months. HIGH-QUALITY 2 STAGE FILTER: Activated Coconut Shell-Carbon Filter + HEPA Filter means this filters more than cheap competitors! EASY TO REPLACE: Simply Unscrew the Eco Four Twenty Personal Air Purifer and replace the filter. It takes only 3 seconds!