Designed for the Alen BreatheSmart FIT50 HEPA Air Purifier, the Alen HEPA-FreshPlus Filter combines three layers of filter technology to purify and freshen the air in your home. Polluted air first passes through Alen's replaceable Pre-Filter to capture large particles, extending the life of the filter. In the second layer, air moves through a True HEPA material that attracts and captures dust, pollen, smoke, mold spores and other airborne pollutants. In the final layer, clean air passes through a thick layer of Alen's Activated Carbon (3 lbs), reducing odors and chemicals commonly found in the air from cleaning products, smoke, cooking, and various other household materials.