Main feature: Amazing Audio with No Strings Attached Equipped with unexpected 40mm ultra-large neodymium backed dynamic driver, this headphone delivers unique sound performance, with crisp and clear sound. With Bluetooth technology, turbine style housing, and Bluedio's iconic surging low-frequency shock let you feel deep bass resonance for superior sound quality, let Bluedio be your tangle-free headphones. Extremely Comfortable & Portable Lightweight stylish design, with adjustable headband and protein leather ear cushion, this headphone gives you lasting comfort. Foldable earmuff design and carrying case for easy storage. Take it with you wherever you go and make Bluedio be a part of your life s best moments. Advanced Compatibility The Bluetooth headset can easily and quickly connect with smartphones, tablets, TVs and other Bluetooth devices within 33 feet. THOUGH, according to the results of Bluedio consumer surveys for three years, 99% issues about Bluetooth connection from the customers' feedback are due to their misunderstanding and improper operation which can always be solved easily after the personalized guidance, Thus: 1. If you can't connect this headphones to your cell phones or other devices, please ask us for a complete FAQ guidance of Bluetooth Headphones, you can find the solutions finally! 2. PLEASE make sure the driver software of receiving adapter is fully updated when connected to PC or laptop, and you need a SEPARATE Bluetooth adapter when connected with TV. You Are in Control You can control all functions of music and calls easily via the buttons on the headphone after simply paired your phone with the headphones via Bluetooth. And you also have access to use the built-in microphone to chat away. Enjoy a cheerful chat with your friends with Bluedio. Specification: Charging interface: Micro USB Battery capacity:3.7V/400 mAh Speaker diameter:40 mm Frequency response range: 10-20000k (Hz) Impedance: 16 ( ) Sensitivity: 11 (dB) Wire length: 1.2 (m) Bluetooth version: 4.1 Connection range: 33 feet (10 meters) Successive working time: about 9 hours Charging time: 2 hours (fast charging) Packing List: 1×Bluedio Headphone 1×USB Cable 1×3.5mm Audio Cable 1×User Manual