Precautions for safe use: 1. Pull a few times before each use, check whether the bar is loose, make sure there is no looseness before use. 2. When the bar rotates, one side of the bar becomes tight and the other side is loose, the hand grip is directed to the side of the bar in the direction of tightening to make sure that the bar will not be loosened because of the rotating force in the process of using it. 3. The longer the bar is extended, the lower the load bearing and firmness will be.