Bluetooth in-ear headphones with built-in hearing amplifier that provide a discreet, personalized sound enhancement and also work as traditional headphones and hands-free device. Thanks to the Bluetooth V4.1 CSR chipset and built-in Automatic Gain Control (ACG), they provide a high-fidelity sound quality. They offer 16 levels of sound enhancement that can be reach via Mode button (turns of the amplifier) and used with or without the music. The headphones are sweat-proof (IPX4) and feature a nano-coating and magnetic lock in the ear-buds for secure hanging around the neck. They also provide an option to adjust the volume of each ear bud individually. Each ear-bud is equipped with removable battery capsule (50 mAh) that can be charged via included 3000mAh Power Pack which can also charge mobile phones and other electronic devices and provides at least 21 cycles of charging two battery capsules. The Power Pack also serves as a place to carry and store the headphones. The headphones also provide voice prompt function in English language, multi-point connectivity and battery meter on iOS system. They come supplied with microUSB charging cable and 9 pairs of interchangeable ear-buds in three sizes (S, M, L) and three styles (bowl shape, double-flange, with tail). Black and silver colour design.