You can charge two devices at the same time. Built-in over-current protection, over-capacity protection, intelligent temperature control, and short-circuit protection. 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 - shows car voltage when FM transmitter is connected to 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 devices. When turned on, it automatically connects to turned off Bluetooth devices.