Dymax Vortex Cooling Fans use vortex technology to generate a high cooling effect. Reduce up to 2-4deg from room temperature. Hang on design suits most aquariums. Air intake chamber – fan concealed internally for safety purposes. Operates on DC Voltage (15V) for low power consumption. Elegant and stylish design. W-8: Max Air Flow 10.5CFM. Max Air Pressure 9.8mmH2O