Twisted pair cables are usually divided into three types based on electrical performance: three types, four types, five types, super five types, six types of twisted pair cables, etc. The larger the number, the newer the version, the more advanced the technology, the wider the bandwidth, and of course, the more expensive the price. The five types of twisted pairs are covered with a layer of shielding metal film, which has better anti-interference performance, but the application conditions are relatively harsh. If shielded twisted pairs are not used, they will definitely be stronger in terms of anti-interference than unshielded twisted pairs. The shielding effect of shielded twisted pair cables is only effective when the entire cable has shielding devices and both ends are properly grounded. So, it is required that the entire system be equipped with shielding devices, including cables, sockets, crystal heads, and distribution frames, while the building needs to have a good grounding system. In fact, in actual construction, it is difficult to fully ground, making the shielding layer itself the largest interference source, resulting in performance that is even inferior to unshielded twisted pair.