GermGuardian FLT4000L Replacement Filter for AC3900, AC4000 and AC4000CA
This combination filter is made of several layers of filtering technology. a true hepa filter captures 99.99% of airborne particles such as dust mites, debris, mold spores, pollens and pet dander. pre-filter captures large dust particles, lint and pet hair. it is suggested that the bulb be replaced every 6-8 months depending on use.