Harman Kardon BT headphones with Bluetooth offer more than a musical escape. They let you escape from wires. They employ AAC and apt-X coding for the highest quality wireless audio streaming and incorporate a built-in microphone and playback buttons on one of the ear-cups. It"s the tangle-free, hassle-free way to enjoy your music. The USB-rechargeable BTs have a battery that lasts up to 12 hours. And unlike other Bluetooth headphones, even when the battery dies, BT headphones will still work when connected by the supplied bypass cable to a playback device. They also feature a closed-back design that keeps outside noise out and keeps your listening experience for your ears only. Lightweight and comfortable, BT headphones let you take Beautiful Sound with you wherever you go