ONA Carbon-Air is the latest in environmentally friendly odor control! The ONA Carbon-Air unit has two 6-inch ports to facilitate airflow into the carbon filter and out through the fan unit. You simply connect the ONA Carbon-Air to your existing ventilation system to distribute throughout your room or air exhaust system. A pail of ONA gel attaches securely to the bottom of the Carbon-Air unit. The ONA Carbon-Air unit is to be used exclusively with ONA gel.