... protection when overloaded 2)In case of the absence of power, a release chain can b Feaures:1)Powerful strength, ... overheat protection when overloaded2)In case of the absence of power, a release chain can be operated door manually3)Loading up ... lamp and remote controller7)Easy installation, legerity design, low noise, small power consumption8)Overheat protection QL-300QL-500QL-600QL-800QL-1000MAX ...