Car FM Transmitter，CHGeek Blurtooth FM Tansmitter Wireless Radio Adapter with Dual USB Car Charger, Hands-Free for Smartphones and Other Devices 

Safety protection. 
The Bluetooth FM transmitter is equipped with an intelligent control chip that provides over current protection, short circuit protection, over voltage protection and intelligent temperature control functions. Not only does it protect your car and your smart devices better, but it also effectively prevents these dangers. 

How to use? 
1. Plug the FM transmitter into the cigarette lighter socket of the vehicle. 
Connect your phone or other devices via Bluetooth / audio cable to the FM 
3.Find an empty channel on your car radio and switch your transmitter to the same channel (87.5 - 108 MHz) 
4. Done! You can now enjoy music and hands-free calls from your car audio system. 

Specifications: 
DC input: 12V-24V 
Output voltage: DC5V +/- 0.25 
Effective Bluetooth range: ≤10 metres. 
FM frequency: 87.5 MHz - 108.0 MHz 
USB charging port: QC3.0 + 5V / 2.4A. 
Bluetooth version: V4.2 
Screen: 1.44 inches. 
TF Card: ≤32G