3Pcs FM Wireless Microphone Pickup Wireless Audio Transmitter FM Emission MIC Core Board V4.0 100MHzFunction: This item make the sound around the microphone into the FM radio, and transmit out to achieve pickup and wireless radio FM transmitter,the launch frequency is adjustable, the core board green components is the adjustable capacitor, change the adjustable capacitor can change Launch frequency, adjustable range covering 88 108MHZ GB FM band. You can use the radio and the phone (the phone with the headset line to do the antenna sensitivity is