You can charge two devices at the same time. Built-in over-current protection, over-capacity protection, intelligent temperature control, short-circuit protection, effectively ensure safe charging. Satellite and Voice Navigation - Bluetooth provides a stable connection, while Noise Cancellation Technology (CVC) provides an amazing hands-free calling experience. Apps for your phone. Detects battery voltage and blue ambient light - displays the car voltage when the FM transmitter is connected to a lighter. Surrounded by blue light, this car charger is safer to operate and more convenient to drive. Compatibility This Bluetooth transmitter is compatible with most smartphones with other Bluetooth-enabled devices. When turned on it will automatically connect a Bluetooth device that has been turned off. Plus, with a wider frequency range from 87.5MHz to 108MHz, you can get more consistent and interference-free music experience.