The expansion joints of the "united multi-directional displacement comb expansion device" comply with the requirements of JT/T723-2008 (recommended industry standard of the Ministry of Communications). In this sentence, the JT/T723-2008 standard is issued by Ningbo An industry standard that Lubao Technology Industrial Group Co., Ltd. participated in writing. Currently, this type of unit-type multi-directional comb telescopic device can be produced by most domestic manufacturers, provided that the drawings issued by the design institute do not specify the RB model.