Rixow B4 Bluetooth Stereo Headset Headphone Earphone Lavalier with Collar Clip Clip-On Wireless Headset (Black) Using APTX audio coding technology, the best music companionsmart for phones and tablet Pure sound without breaking sound Using audible multipoint technology, you can get signal searched faster and wider. Paring two Bluetooth devices with only one headset, no need of manually switch Bluetooth 4.0 achieves the goal of energy conservation. It also provides the great stereo sounds and clear speech. Up to 16 hours of music and talk time/ Up to 250 hours standby time.