You Can Use the Clutch Key to Open and Close the Door Manually When the Power Is off: There Is Also a Way to Open and Close the Door When the Power Is off. When the Door Encounters Obstacles During Opening and Closing, It Can Automatically Stop or Rebound: Very Safe. You Can Set the Automatic Closing Time: to Make Your Life Easier. Reliable Electromagnetic Limit, Easy to Adjust. The Built-in Maximum Motor Running Time (Mrt) Can Be Adjusted to Provide Multiple Safety Protections.