Introduction: It's an invisible and wireless mini earphone. It's very difficult to be found by others when you get it in your ear. Generally, it's used by reporters, journalists, investigators and so on. Working Procedure: The transmitter, namely the wired earphone which is connected to the phone, can transmit the signals to the mini earphone well with little disturbance. And the mini earphone can receive the signal very well. And what's more, the wired earphone can be connected to Nokia, Samsung, Motorola and other branded mobile phones.