This soldering FM radio transmitter kit is well made, after you finished soldering and installation, use the microphone or the audio cable, you can really broadcast to a FM radio, which is very cool EASY AND FUN TO SOLDER Two IC chips were both soldered well on the board, no worry about the SMD soldering part. Clear marks and solder pads will also allow you finish it easily. No matter it’ll used to be an education kit for teaching electronics or soldering it with your lovely kids, you will have awesome time, they will definitely be proud of themselves when done, especially when you have fun with it! SIMPLE TO USE WITH A FM RADIO It can be used with our radio (ASIN: B07YH8V2KS). Long short press the two buttons of the transmitter or adjust the radio to keep their frequencies the same. (Try to avoid the dense and strong frequency band where the local radio station is located.) The radio has no sound when matched, plug the microphone or audio cable into the audio interface, you can hear your voice or audio equipment from the radio. For experiencing it better, please try to use it in an open area as much as possible because of the indoor electromagnetic wave environment is complicated. Some Parameters You May Care 1) Operating frequency: 87108MHz 2) Microphone length: 100cm 39.37inch 3) Audio Cable length: 50cm 19.68inch 4)Antenna length: 31.5cm 12.4inch; 5section retractable type; 360degreerotated 5) Receiving equipment: audio radiomobile phone with radio function 6) Transmission distance: 0100m We also put colorful paper instructions in the package for you, any needs or questions, please feel free to let us know Have fun with the FM radio transmitter kit!