Receives the signal from any BT enabled device and sends to any amplifier with low level inputs or a head unit with an AUX input. Mounts anywhere. Control-less – Uses the controls on the BT device for Play/Pause, Track & Volume adjustment. Power-saving feature – BT UR turns off the amplifier if music is paused for more than 10-20 seconds. Powers amp on when play is resumed. Indicator lights inside the translucent case: Blue light indicates BT pairing status. Red light indicates amplifier status.