The AT-WLA1 wireless headphone adapter cable utilizes Bluetooth® technology to turn wired in-ear headphones into wireless headphones. The cable works with any in-ear headphones equipped with A2DC (Audio Designed Detachable Coaxial) cable connectors. The AT-WLA1 features an in-line mic and controls, allowing you to answer calls, adjust volume and control music playback on compatible smartphones and other devices. The cable's behind-the-neck design conveniently situates the mic and controls for easy access and places the battery case on the upper back where, if desired, it can be attached to your shirt collar with the included clip. Ear hooks are also included for use with headphones designed to wrap around the ears. The internal battery powers the headphones for up to 7 hours (200 hours standby) and can be recharged with the included 30 cm (1') USB charging cable.