Active Air -Filters offer features and performance that rival the competition - but at a value price. All filters are maintenance free and feature long-lasting activated virgin charcoal that keeps your air odor-free. - Corrosion-resistant galvanized steel - Changeable Velcro pre-filter to collect dust and airborne particles - Shrink wrap to protect the charcoal and keep the filter clean. Active Air-FILTERS FEATURE: - High grade activated charcoal to guarantee maximum odor control - Large surface areas and 2.5" thick carbon bed results in optimum odor control and maximum efficiency. - No maintenance required - Charcoal is carefully packed to insure a consistent and even air flow throughout the carbon bed for a full usage of the filter and its durability. - Pre-filter to remove airborne particles and dust. Fitted with Velcro for easy removal. Recommended airflow: - 200 CFM Minimum - 400 CFM Maximum Compatibility Chart