The Can Fan RK series of fans use the same motors and airflow control as the RS range. They are encased in a moulded durable polymerbody. The Swiss made motor,together with the propeller design is enabling this type of fan, to deliver astrong airflow while making less noise. The addition of the speed controller adds versatility. Each speed setting is factory set and calibrated to produce the most efficient output specific to each fan. No need for extra electronic speed controllers or transformers. Flexibility when the grower needs to make seasonal adjustments. Convenience: increases the ability to match fans with a larger range of filters.