How to use the car transmitter: 1. The FM frequency of the machine should be adjusted to the same frequency as the radio frequency. (For example: the radio frequency is 87.5, and the machine needs to be tuned to 87.5) 2. The radio should be tuned to an idle channel (a channel without a radio station) 3. The frequency range of the machine is 87.5-108. The channels in each region are different. If the high frequency is not enough, you can change the low frequency. Descriptions: Operating voltage: 12-24V Dual USB output: 3.1A PD TYPE-C Play format: MP3/WMA Bluetooth version: 5.0 Frequency response: 20Hz~15Khz Bluetooth transmission distance: 10-15 meters Color: Black Specifications: 1.Double USB PD fast chargingCan charge multiple mobile phones at the same time. 2.High quality music playback wireless pairing 5.0 transmission without distortion, advanced noise reduction technology to ensure sound quality, crystal clear sound. You can play music on your car stereo through wireless pairing /USB FLASH drive (32GB)/TF card (32GB). Note: USB flash drive or TF card supports WMA MP3 WAV APE FLAC music format. 3.Hands-free callbuilt-in microphone and noise suppression (CVC) technology, make hands-free call clearer, automatically switch from music playing state to hands-free state when answering. One click to answer/end the call. It"'"s easy to drive. 4.Wide compatibilityWireless pairing FM transmitter supports all devices that support wireless pairing, suitable for iPad, iPhone, Google, LG, tablet PC, Android and other devices with wireless pairing connection, easy to set up and use. 5.7-color RGB LED BacklightThis wireless pairing radio transmitter supports 7-color LED backlight and you can get a visually stunning color display. Package Included: 1 * Bluetooth FM transmitter (With Retail Box) 1 * User Manual