Easy to install. Small maintenance is need. Able to ventilate polluted air, dust, and smoke in factory or wherever. Able to Install in the factory. Able to install in several ways.
Shutters are automatically on and off for safety and orderliness.
Shutter is waterproof. Able to Install in the factory. Able to install in several ways. Shutters are automatically on and off for safety and orderliness. Shutter is waterproof.