This Range Hood Recirculation Kit can be used when venting to the outside is either not possible or not desirable. This recirculation kit with charcoal filters can be used to freshen air and recirculate it back into the kitchen.This recirculation kit is an accessory that can be used across several brands; check to see if your model number is compatible. Installing this accessory will require basic hand tools and novice repair experience. Helpful Tip: For optimum performance of your vent, change the filter at least once per year or when a loss of airflow can be detected.