A musical instrument cable that is functional for use while walking around and playing an electric guitar or other electric instrument. A plastic bushing encircles the pin and extends into the slot. The synchronization identifier is used for the purpose of synchronizing communication between a Mobile Station and a network. The controller, coupled to the processing and metrology tools, determines whether the difference between the measured film thickness and a preset film thickness exceeds a preset value, and determines a second processing duration of a second removal process according to the measured and preset film thickness and the first processing duration.