The so-called threading refers to the whole body being engraved with threads. The outer thread joint of the whole body engraved thread can freely adjust the position of the connected two end tubes. If used horizontally, it becomes a "pull outer wire joint", which can be used to limit the degree of freedom of the pipeline in the horizontal direction; The wire used in the vertical direction is called a "hanging wire". The upper end of the wire is connected to the top pipe, and the lower end is hung down. Generally, fire sprinkler pipes can be used, etc. The significance of using a wire is that it can freely adjust the height of the suspended pipeline.