Vornado AQS25 True HEPA Air Quality System Recommended for closed rooms up to 310 square feet True HEPA filter at least 99.97 percent effective; prefilter also reduces odors Removes smoke, pollen, dust, animal dander, dust mites, molds, bacteria, viruses Portable; 22 by 13-3/4 by 10 inches; works behind furniture Three speeds for different-size rooms; dirty-filter indicator