bulit-in megaphone, clear timbre, adjustable volume Bluetooth Car Kit 1. Bluetooh 2.0 transmission, in good quality sound for telephone. 2. 3.7V standard chargeable lithium battery, can keep power on for a long time. 3. 2.5W bulit-in megaphone, clear timbre, adjustable volume. 4. With phone call saving function 5. With car charger for accessories Bluetooth Handfree Car Kit