The MM 400-X is a state-of-the-art stereo Bluetooth headset for multimedia mobile phones. With one press of a button, you can quickly switch between calls and music delivered in superb stereo sound. The invisible high-performance microphone ensures that conversations are clear, making this headset the perfect all-in-one sound solution. As an added benefit, the MM 400-X enhances the latest apt-X enabled mobile phones and computers with supreme CD-quality sound.