Summary: The Multi Tech A4000 brings air purification to a new level by adjusting the fan speed to match requirements reported by its two on-board sensors when operating in automatic mode. This in turn extends the lifespan of the product and its filters by not maximizing the use of these resources when not needed. Beginning with its quiet, powerful 106 CFM (45 db at the highest fan setting), the Multi Tech A4000 spells quality and performance from the ground up. As air is drawn into the Multi Tech A4000, a washable pre-filter removes most larger particles, protecting downstream filters in the process. The air then passes through an activated carbon filter where chemicals, gasses, odors, and cigarette smoke meet their match and continues on through a true HEPA filter (rated 99% effective at 0.3 microns) where dust, dust mites, mold, fungi, allergens, and bacteria are removed or neutralized. Next, the air passes through a cold catalyst filter, removing additional pollutants including chemicals and various micro-organisms, and then travels on through the cold catalyst filter where micro-organisms are destroyed. Finally, the air exits the unit bathed in trillions of negative ions which seek out and destroy additional air borne particles and bacteria in the surrounding air.