Shutter:with a centrifugal system which can ensure the shutter open and close automatically, and makes it dustproof waterproof .
Motor:the high efficient and energy-saving motor with protection grade :IP55 insulation class:F
Belt:Automatic tensioner to prevent the belt loosing and dropping off
component :centrifugal shutter system and other fitting of shutter made of nylon high quality engineering pleastics 100%.