Electric shutter doors are doors piece together a series of multi-joint activities, the starter motor is driven by the group, shutter doors in a fixed slide, scroll to the top of the door to the center of rotation of the upper and lower door. Open, closed, low noise, does not produce a high-decibel noise; can open locked in any position. Actually use, safety, aesthetics, ease of installation are better than conventional rolling gates. Also optional silencer motor, and General Motors, so that the door muffler volume more comfortable, safe and convenient. http://w136115.jdol.com.cn/gongying/8063100.html