Wireless BT Headphone is characterized by Advanced BT 4.1 technology, built-in high-grade Microphone & Speaker, hands-free function and lightweight design, designed for sports enthusiasts.  Features:Wireless BT 4.1 ensures transmitting strong signal in high quality and high speed, delivering high-fidelity music.In-ear headset with ear-hook, brings you immersed music enjoyment and not easy to fall.Built-in microphone enables hands-free calls to set free your hands when doing sports. It also supports multi-point technology.Easily control playing / pausing, adjusting the volume, previous / next songs, answering / rejecting / ending calls.Ergonomic design guarantees wearing stable and comfortable when exercising, running, climbing and other outdoor sports.Specifications:Model Number: 56SBT Version: 4.1                                                              Support: HFP, A2DP, AVRCP                                                                                               Working Distance Range: 10m                                                    Frequency Response: 20-20KHz                                     Impedance: 32ΩSensitivity: 105dBHigh-quality 3.7V / 60mAh Rechargeable Lithium BatteryCharge Time: about 1.5 hours                                                              Standby Time: about 100 hours                                                             Talking Time: 2-4 hours                                                              Music Time: 2-4 hours (The music volume will affect the time)Charge Port: Micro USBColor: Black, Blue, Red (Optional)Cable Length: Approx. 67cm / 2.19ftHeadphone Weight: 16g / 0.56ozPackage Size: Approx. 12.5 * 11 * 3cm / 4.92 * 4.33 * 1.18inPackage Weight: 30g / 1.05ozPackage List:1 * Headset   1 * Micro USB Charging Cable1 * User Manual