• Large Work-space Air Purifier features Filtrete air cleaning technology to help purify the air in your office • Designed for conference rooms or other large work spaces up to 320 square feet (16" x 20") • Three-stage filter design includes both Filtrete filter media and ionization for airborne particulate removal • Activated carbon filter for odor reduction and ionization removes smoke, dust, and pollen from air • Office Air Cleaner offers three fan speeds, ionizer on/off switch, and filter change reminder • Filter effectiveness lasts up to three months under normal conditions