1、It makes the sound around the microphone into the FM radio and transmits out to achieve pickup and wireless radio FM transmitter. 2、Wide voltage range: 0.7-9V. Under the condition of 9V and use of 70cm antenna, the launch distance is 50-100 meters in open space (depends on the actual environment). 3、88-108MHz adjustable launch frequency, more flexible to use in different situations. 4、Widely used in voice pickup transmit, audio MIC, the elderly and children sleep monitoring, etc. 5、Sturdy material and long lasting. Compact and lightweight. Specifications: Color: Green Operating Voltage: 0.7V-9V Frequency Adjustment Range: 88-108MHz Transmit Distance: Under the condition of 9V and use of 70cm antenna, the launch distance is 50-100 meters in open space (depends on the actual environment) Relationship between Working Voltage (volts), Supply Current (mA) and Transmit Power (dBm): 9V, 24mA, 10.2dBm (that is, 11mW) 8V, 21 mA, 9.5dBm 7V, 19mA, 8.5dBm 6V, 17mA, 7.1dBm 5V, 14mA, 6.1dBm (about 5 mW) 4V, 12mA, 4.5dBm 3V, 9mA, 2.2dBm 2V, 6mA, -1dBm (about 1mW) 1.5V, 4.2mA, -4dBm (about 0.5mW, the general family environment launch is sufficient, small green radiation!) 1V, 2.4mA, -9dBm 0.7V, 0.9mA, -20dBm (that is 0.01mW) Item Size: Approx. 3.5 * 1.5cm / 1.38 * 0.59in Package Size: Approx. 5 * 3 * 1cm / 1.97 * 1.18 * 0.39in Package Weight: Approx. 3g / 0.11oz 1 * FM Transmitter Module Board