Audio-Technica ATH-S700BT SonicFuel Bluetooth Wireless Over-Ear Headphones Offers clear, full-bodied audio reproduction with Bluetooth wireless operation that pairs with up to 8 Bluetooth wireless devices Built-in headphone amplifier ensures clear and accurate sound reproduction from the wireless signal Easily answer calls, adjust volume and handle playback of music and video with mic and music/volume controls Internal battery provides six hours of continuous use (200 hours on standby) on a full charge The headphones feature 40 mm drivers for powerful sound and efficient signal transfer Housings contain an acoustic chamber that's separate from the electronics and helps to maximize driver performance