Features: BT Connection: With BT function, easy to pair with almost all the BT-enabled audio devices, freely to enjoy wireless music and HD hands-free calls. Stereo sound quality: 40mm dynamic drivers transmit high fidelity and powerful bass, bringing great sound effect, just immersing in the music world. Line-in function: Connect to the music players (such as, MP3 / MP4, etc) without BT function via the included 3.5mm cable. Long Battery Life: Built-in 400mAh rechargeable battery lasts up to 10 hours of music playing time and 300 hours of standby time per charge cycle. Ergonomic Design: Foldable and adjustable headband length, soft leather ear cushion, comfortable to wear and easy for storage.