... rust resistant capability, 2.energy saving, 3.easy to operate Roof ventilator Character: 1. Zinc of steel:180g/m2, stong rust ... kind of turbine can be installed on many kind of roof , easy to operate. 3. Double bearing (1)with fireprollf nylon ... motivates system can ensure ventilator work more smoothly and efficiently. Non-power roofing ventilator