Note This is a DIY kit you need to assemble it Click here to download the assembly instruction Feature Kit model RF 03PLLKit use private radio car audio transmitter cable audio to wirelessOperating voltage DC4 6VOperating current 20mA 40mALaunch distance 20 80 meters barrier affected by production level Transmit frequency 87 108MHz 14 frequency through the DIP switch to change the frequencyPower indication Yes less than 4V Auto light offAntenna 300mm soft wire you can also modify to launch farther distanceOscillation mode PLL phase locked loopFrequency stability zero driftSound quality excellent stereo two channel transmission automatic gain controlMicrophone Yes PCB onboardMicrophone distance 1 meter normal speechMicrophone and audio input conversion mode pull out the audio line microphone automatically workPCB size 74mm 52mmPackage includes 5 x DIY FM Stereo Transmitter Module KitLow frequencyD0D1D2D3FrequencyLLLL87 7MHzHLLL87 9MHzLHLL88 1MHzHHLL88 3MHzLLHL88 5MHzHLHL88 7MHzLHHL88 9MHzHigh frequencyLLLH106 7MHzS3 dial to H108MHLLH106 9MHzLHLH107 1MHzHHLH107 3MHzLLHH107 5MHzHLHH107 7MHzLHHH107 9MHzSoldered PCB for reference only