This product will be put the sound around the on-board microphone into FM radio radio signals emitted,To achieve pickup and wireless audio FM transmitter Product launch frequency is adjustable,The green component on the core board is adjustable capacitance Change the adjustable capacitor can change the transmission frequency,Adjustable range covers the 88 – 108 MHz GB FM section You can use the radio and mobile phone as a receiver This product is widely used in voice pickup transmission,audio MIC,sleep monitoring,and other suitable occasions Color:green +silver Material:PC +metal Operating voltage:0.7 – 9 V Frequency adjustment range:88-108 MHz Transmission distance:50 – 100 meters(9 V when using the 70 cm antenna conductors) Package Contents: 1*Microphone FM Transmitter Module Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.