It is mainly used for walkie-talkies of brands such as MOTOROLA (such as models like XiR P8668i and GP328D +), serving the purpose of identification and operation. The black main body paired with white marking lines enables users to intuitively identify the current volume or channel adjustment position. By rotating this knob cap, the volume of the walkie-talkie can be adjusted or the channel can be switched. It is an important small component that ensures the convenience of walkie-talkie operation and the realization of its functions.