Features: Multifunctional: Equipped with features of BT connection, TF card music playing, AUX-IN wired music playing, FM radio, and hands-free call with Microphone. BT Connection: With BT4.2 function, easy to pair with almost all the BT-enabled audio devices, freely to enjoy wireless music and hands-free calls. AUX-IN Function: Connect to the audio devices (such as MP3/MP4, Laptop, etc) without BT function via the 3.5mm audio cable (NOT included). Long Battery Life: Built-in 250mAh rechargeable battery lasts up to 10 hours of music playing time per charge cycle. Ergonomic Design: Adjustable headband length, foldable soft leather ear cushion, comfortable to wear, and easy for storage. High-sensitive Mic: HD microphone reduces ambient noises and grasps the detail of voice. You can get high-quality hands-free phone conversation. Specifications: Brand Name: NIA Model Number: S4000 BT Version: 4.2 Support Profiles: A2DP/ACRCP Operation Range: 10 meters (no obstacle) Frequency Response: 20Hz-20KHz Impedance: 32Ω Sensitivity: 108±3dB FM Frequency: 87.5-108MHz Music Format: MP3, WMA, WAV Speaker Unit: 40mm Battery Capacity: 250mAh (depends on music volume) Working Time: about 10 hours Standby Time: about 200 hours Charging Time: about 2 hours Charging Port: Micro USB Color: Black