Wires are buried in walls and must be threaded. Generally, PVC threading tube/PE threading tube are optional: affordable, flexible, and good insulation performance. In fact, the general family chooses PVC threading pipe/PE threading pipe is very good, but choose a strong one, the simple way is to step on it with your foot, and the one that will not be crushed is good. A final reminder: no matter what kind of threading tube is used, the wires must not have connectors in the tube.