This variable-speed, downblast roof mount ventilator allows up to 80% useable turndown and eliminates the need for a speed control. It features electronically commutated motor (ECM) technology, a variable speed motor, and a potentiometer dial pre-mounted on the motor to control speed. It addition to quiet and cool operation, the motor does not require belt or pulley maintenance, and is engineered to offer long service life due to lower running temperatures.