The active carbon filter of intense pure air bedroom size auto purifier has powerful odor removal benefits, pre-cleans the air before it reaches the HEPA filter and catches gas and chemical pollutants. Needs to be replaced every year Features : Active carbon filter eliminates odors and harmful toxins such as paint fumes*Replace once a year*Room coverage up to 400 sq ft*Fits PU4020 intense pure air Purifier Product dimensions : L: 16.5 W: 7.4