Large Ring Knob, More Convenient to Adjust With integrated ring knob, you can easily turn ring knob to adjust the frequency, changing radio station more quickly and accurately. Also, simple and compact buttons layout in front of the Bluetooth FM transmitter makes you clear at a glance, which provides more convenience for you to use its various powerful functions. SIRI Google Assistant for Convenience5.0 Bluetooth FM transmitter supports voice commands to ensure safe driving. You can stay fully focused on the road by waking up amiable Siri or Google Assistant to make phone calls, send texts or get driving directions, enjoying complete voice-control, more convenience and safety to get your things done faster! Bluetooth 5.0 & Wide Compatibility With advanced Bluetooth 5.0 chip, this FM transmitter Bluetooth provides faster pairing and more stable music and call than other normal product. Also, its wide compatibility supports all Bluetooth enabled devices, such as iPhone, iPad, tablet, Sony and other Android smartphones, and you can use it in all of cars/trucks (12-24V). Multi-Safety Protection for Devices Car Bluetooth adapter’s built-in intelligent chips prevent your charging devices from over-current, over-voltage, over-heat and short circuit protection. Also, the low noise and low ripple output design can reduce the loss of electronic devices, which will strengthen safety and avoid possible danger for your smart devices. Intelligent Detection of Car Voltage Adopting intelligent voltage detection chip, the Bluetooth FM transmitter can monitor your car voltage in real time. 12.0-12.8V: Normal voltage before the car starts; 13.0V-14.8V: Normal voltage after the car starts; Lower than 12V: Lower than 12V before starts, please as soon as possible replace the battery. Package Includes 1x FM Transmitter 1x User Manual