The Nakamichi® Bluetooth® Wireless Headphones deliver rich and powerful audio. They feature a wireless microphone, Bluetooth 4.0 and soft cushion headphones for comfortable listening. Built-in microphone technology allows for hands-free calling with a pure connection to your wireless device for clear, hands free calling. Built-in, USB rechargeable lithium-ion battery provides 7 hours of uninterrupted listening. And when the battery dies, the included 3.5mm Aux-in cable allows for passive listening. Foldable headband for ultra portability for travel, work and anywhere in between.