it allows talk time for 4.5 hours3.HD clear sound qualityThe featured HD Voice it also ensures a more natural and clear audio experience.The noise isolating in-ear design enables you to listen at safer volumes,Website:http://www.smartcoolproduct.com, improving audio quality and keeping your tunes to yourself.3.Connect two phones simultaneouslyYou can connect two smartphones with this QCY QY7 Stereo Bluetooth Headset,easy to control calling by switching these two phones.4.Convenient to useHear m