Detachable Replaceable Battery (Included)Bluetooth Headphone , Bluetooth V4.1 Wireless Sports Headphone, Stereo Bluetooth Headset , Compatible Most Digital Equipment with Bluetooth (Blue) Detachable dual battery: 200mAh(Both) big capacity rechargeable battery, which ensures long working time Bluetooth V4.1 wireless headset: The latest technology of Bluetooth and backward compatibility V3.0, V2,1 V2.0 and so on Stable signal transmission, barrier-free 10 meters transmission distance(depend on the environment), wireless and chainless High technology CSR8635 chip, excellent stereo and verisimilar sound effect, creating good listening atmosphere Mini and portable sizeLightweight, With ear-hooks, it will lay on your ears stable while you are driving or doing sport