... resistant capability, 2.energy saving, 3.easy to operate Roof ventilator Character: 1. Zinc of steel:180g/m2, ... long severce life. Also stainless steel , Galvalume material for choice. 2. Multi-angle turbineturbine can be altered, This ... of turbine can be installed on many kind of roof , easy to operate. 3. Double bearing (1 ... ensure ventilator work more smoothly and efficiently. Auto Roof Ventilator