Note: This earphone is specially designed for exercising: running, biking and hiking. While you are listening to music, you are able to hear your surroundings, preventing any potential danger. Since this earphone uses bone technology, the sound quality is not one of its prominent features. Therefore, we do not recommend this product if you are merely looking for a earphone with superb sound quality. Specifications: Speaker type: Bone conduction transducers Bluetooth version: V4.2 Charging time: 2hrs Material: Titanium alloy & TPU Frequency response: 20Hz~20KHz Battery: 180mAh lithium polymer battery Standby time: up to 10 days Play time: up to 6 hours Charge port: Micro-USB Weight: 1.3 oz Waterproof grade: IP55 Package content: -- 1 * headphones -- 1 * usb charging cable -- 1 * user manual -- 2 * noise-proof earplugs ApexJoy bone conduction technology is aim to transmit audio waves to the inner ears through the skull, bypass the eardrums completely. Place them on your cheekbones, just in front of your ears. This leaves your ear canals open, allowing you to remain alert and aware of ambient sounds while enjoying your music or tune in to calls.