Smof Bluetooth 4.1 Hands-Free Car Kit/Wireless Bluetooth Audio Music Receiver with Built-in Mic,3.5mm Stereo Output,USB Charging,3M Adhesive Base for Smartphones(Black) Built-in microphone,you can receive your calls with your hands free when your are driving.Bluetooth Hands-free Car kit help to answer and receive calls for your iPhone,BlackBerry, Samsung,etc Help to listen to music wireless in your car and easily control.Next/Previous song,volume Up/Down.When you start your car,it will power on again and it can connect automatically Some cars may have the noises caused by Ground Loop,you will enjoy good quality sound when use it,it can reduces noise and hum caused by ground loops Double-link:Support multi-point connection technology;Connect two phones Simultaneously.Automatically connect to the last connected phone Working range will be 10meters (about 30 feet);It should be powered by USB port first.The car charger isn't included in the package,you can choose our Smof Car Charger or other chargers as you like