Built-in HD and sensitivity microphone: Idea for in car calling or working use?? perfect for stealth listening or watching at work</br>Built-in 50 mah polymer battery?? up to 4 hours of continuous talk time?? 3.5 hours of music time?? only need to charging 2 hours?? do not over 2 hours</br>Pairing instruction: Press and hold the button until the voice states " to pair" or the LED light flashing red and blue</br>Notice : The Bluetooth is only for one ear?? not a pair?? due to the difference of people's ear?? this earphone maybe not fits everyone</br></br>Product Description</br></br>Love life?? love music get rid of the wires when exercising this earphone is Bluetooth v4.0 + edr?? fully backward compatible with most Bluetooth version device (v4.0?? v3.0 + edr?? v2.1 + edr?? v2.0 + edr?? v1.2?? v1.0 etc.). Just make sure your phone (or other device) is Bluetooth device pairing instructions press the power button of the headset for about 8 seconds or longer until you see the blue & red ligh