Brand: Bluedio HIFI Level Stereo Sound Effect: Built-in 2 subwoofers of 100Ω with 50mm diameters, 6 3D tweeters , providing you thestrongest 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. 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 USB files transfer: Insert SD card, you can transfer data, movies, music directly from computer to SD card. Trendy and powerful outlook: Elegant piano paint process. Extremely portable flexible headband: You can fold it into a smaller size. 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 100Ω, 6 pieces of 32Ω 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 Features: 1.Power amplifier 2. 8 sound track 3. HIFI Level 4. 2 built-in large sound speaker with diameter of 50mm and 6 3D speaker