HIFI Level Stereo Sound Effect: Built-in 2 subwoofers of 100¦¸ with 50mm diameters, 6 3D tweeters , providing you the strongest sound effect that you ever heard before; V3.0 Bluetooth Technology: Bluetooth V3.0 version provide you 8 times faster connection speed than V2.1. After pairing, Bluedio R supports hands free talking, music streaming, VOIP, SKYPE online talking, etc. Support LINE-IN: Can be connected with 3.5mm cable and stream music directly from mobile, computer, tablet, etc. Support SD card. Extremely portable flexible headband Adjustable: The headband can be adjusted into different length to suit for different customers. Maxim amplifier: Amplify sound effect, plus noise cancellation. Ultra-Strong: with taking time up to 35 hours and strong standby time 325 hours. Function list of headband headphone: 1£®Bluetooth Version 3.0 2£®Sound-proofing 3£®LINE-IN (Stereo wired audio) 4£®Support MP3 Player 5£®file access by USB 6£®Support Micro-SD Specifications: 1£®Charged by Micro-USB 5V, Charging galvanic current 300mA 2£®3.7V 700mAH polymer chargeable battery 3£®Bluetooth freq: 2.402-2.48GHz 4£®Class1,2,3 Support without external power amplifier 5£®3D speaker combination, 2 pieces of Subwoofer speakers with 100¦¸, 6 pieces of 32¦¸ Tweeters 6£®Sensitivity: 120db 7£®Frequency:15~40KHZ 8£®Power consumption of Bluetooth stereo: 28mA 9£®Static State Current: 12Ma(MAX4410+MAX9722) 10£®Maximum Current: <30mA 11£®play=" time:=" 20hours