Tests by the Hammacher Schlemmer Institute proved this tabletop air cleaner to be The Best because it had the highest clean air delivery rate (CADR) and produced minimal noise in spite of its superior air intake. The Institute commissioned an independent laboratory to determine CADR, and The Best Tabletop Air Cleaner's scores for filtering pollen, dust, and tobacco smoke were 151%, 73%, and 87% higher respectively than lesser models. On its highest setting, The Best unit produced only 18.9 dB, far superior to noisier models that generated up to 35.6 dB. Scoring highest for features, The Best Tabletop Air Cleaner has a five-stage filtration system that includes a HEPA filter that removes 99.97% of particles larger than 0.3 microns and an organic fiber sterilization filter--the same technology used in hospitals--that eliminates 97.7% of airborne bacteria. Designed for rooms as large as 450' sq., the air cleaner is only 8 1/2" wide, allowing unobtrusive set up on a desk or tabletop. Plugs into AC. 12" H x 17 3/4" L x 8 1/2" W. (10 lbs.)