Estimated ship date is 2/18/2008. Fits the 501 and 601 Blueair Air Purifier. Blueair recommends changing these smokestop replacement air filters every 6 months. One complete set of replacement air filters includes 3 enhanced HepaSilent (equal particle efficiency) replacement air filters that remove dust, pollen, bacteria, pet dander, mold spores and other airborne particles. The particle filter is made of polypropylene, which mechanically filters out airborne particles. To maximize filter effectiveness, particles are negatively charged before reaching the filters. The smokestop replacement air filters additionally contain more activated carbon than the standard filter which allows removal of more smoke, odors and gases from breathable air..

The 501 effectively purifies air in rooms as large as 620 square feet. Using patented two-stage HEPASilent™ air filter technology, it captures 99.97% of the tiniest 0.1 micron particles on level one, including allergy-provoking pollen grains, dust mites, mold spores and pet dander particles. Our efficient SurroundAir™ vent system delivers exceptional air exchange (up to 500 cubic feet per minute) without annoying drafts, performance that earned the 501 Best of Class ranking in independent AHAM testing of Clean Air Delivery Rate.

Easy maintenance: simply open the unit`s lid, lift out and drop in this set of 3 replacement air filters every 6 months.

IMPORTANT! Use only Blueair filters to ensure proper functioning and to qualify your unit for full warranty coverage.