Long Transmission Distance. 9V work when using the 70 cm antenna conductors, open the local firing range 50-100 meters, the actual situation depends on the environment. for electronics enthusiasts upgrade or replace the chip. Feature - Color: As Shown. - Material: Plastic+Electronic Component. - Size: 3.5 x 1.5 x 1cm. - Operating voltage: 0.7V - 9V. - Frequency adjustment range: 88-108MHZ. - Relations Working voltage (volts) and supply current (mA) and transmit power (dBm) is as follows: 9V, 24mA, 10.2dBm (that is, 11 mW) 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 1 milliwatt) 1.5V, 4.2mA, -4dBm (about 0.5 mW, the average family environment launch sufficient, small green radiation ) 1V, 2.4mA, -9dBm 0.7V, 0.9mA, -20dBm (that is 0.01 mW). - Listen with any FM radio or radio scanner. - Many uses, baby monitor, nature monitoring, home security, use to add sound to home camera recording system or listen to sound from a parked car. - Transmitting very clear sound to distance about 10-30 meters.