Smof Bluetooth CSR4.0 Hands-free Headset + Receiver 2-in-1[Alternatively Choose the Headset or Car Audio System to Answer Calls/Play Music]with In-car Charging Dock&3.5mm Output for Smart phones Two ways to receive your calls or listen to music in the car:you just pick up the headset and wear it you dont need to wear the headset,you will hear the voice from your car speaker Hands-free Calling:For your Car Audio System,pair it to your cellphone and you can answer your calls with your hands free when you are driving. Listen to Music Wireless:When successfully paired to your cellphone,you can enjoy your favorite music from the BT headset or Car Audio System as you like.Suggestion: Some cars may have the noises caused by Ground Loop,you will enjoy good quality audio when use it with Smof Ground Loop Noise isolator, and it can completely eliminate noise and hum Easy Operation:Pick up to answer a call automatically;When you start your car,It will connect to the last paired device automatically.No need to pair to it again[Important Notice:Before using it for the first time,you should long press the power button until the red and blue led light will flash alternately,it is pairing state] You can stick the charging dock on your car as you likeit will charge automatically when put the headset on it.The car charger isnt included in the package,you can choose our Smof Car Charger (2.1A/4.2A)or other chargers as you like.