Features: Roller door opener used for open and closed the roller door of supermarket door storehouse,cinema.hotel and factory and so on,it acan be operate by electrcity and manual. door opener structure and function features: 1) it can be driven by electricity to operate the functions of moving up and down.precise limit by the limiter controlled qutomatically. 2) operated by manual when out of power 3) the enwinding group of the motor is with overheat protect equipment,When the temperature is up to 110 degree centigrate.it will cut off the power supply automatically to protect the motor.when the temperature reduce to 70 degree centigrade,it can be used again. 4) low noise,small shaking.lower power exhaustion.