The professional fans with massive air output are ideal for use where large volumes of air need to be circulated in a short time. In addition to restaurants and large kitchens, these fans have also proven to be highly effective in workshops and warehouses. The automatic shut-off flaps prevent unwanted drafts and heat loss when the fan is stationary. In conjunction with the speed control, not only is individual performance regulation possible, but also a reversal of the airflow direction.