ona carbon-air 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.