SmokeStop Unit is the ideal choice for allergy sufferers and other health-conscious individuals that need high-efficiency particle removal plus gas and odor control. The SmokeStop filter is a progressive carbon filter with a honeycomb-type structure that improves airflow and has hundreds of odor and gas absorbing carbon pellets. The filter contains 2.0 lbs of coconut shell activated carbonimpregnated with a 70/30 blend of Potassium Hydroxide (KOH) and Potassium Iodide (KI). The carbon eliminates volatile organic compounds (VOC), which are responsible for odors.