It looks big but its very light and hollow. It takes air moving towards the rear and forces it through the motor. Fans have a limited pressure they can work with so depending on the ventilation through the motor there is a vent to relieve pressure to keep the fan at optimal pressure. Significant air moves diagonally from the top front of the motor to the rear back of the motor. Hot air exits the chassis from underneath and the passenger side of the motor to keep the rotor bearing temperatures down.