The ATH-WS99BT wireless headphones combines powerful Solid Bass reproduction with Bluetooth® wireless operation. The headphones are equipped with a mic, and music playback and volume controls, allowing you to easily answer calls, adjust volume and handle playback (play, pause, fast-forward and rewind) of music and video on compatible smartphones and other portable devices. The headphones remember up to eight devices and automatically connect with the last paired device. A 1.2 m (3.9') smartphone cable with mic and controls is also included to provide a standard wired connection that can be used in areas where Bluetooth wireless use is prohibited or when battery power is low. The ATH-WS99BT headphones also employ aptX® sound-improvement technology, specifically created to yield the best-possible audio performance over Bluetooth transmission. Like all Solid Bass headphone models, the ATH-WS99BT delivers incredibly full and textured bass, along with the astonishing clarity and fidelity. The headphones feature 53 mm drivers for powerful sound and efficient signal transfer. The audio is given an additional boost from the high-quality, built-in headphone amplifier. The precision-machined aluminum housings eliminate vibration for extremely accurate sound reproduction, while the innovative Double Air Chamber System naturally extends bass response without compromising mid- and high-frequency content. The ATH-WS99BT wireless headphones are equipped with an internal lithium polymer rechargeable battery that provides six hours of continuous use and up to 200 hours in standby mode. A 1.0 m (3.3') USB charging cable is included.