The second of two S1 Audio Mobile headphones, the S1 Audio Mobile 2 is an upgrade from the S1 Audio Mobile 2 in that it features two (versus one) retractable earbuds and a unique switch that makes it simple for users to switch between listening to music and speaking on the phone. In fact, the Mobile 2 is designed to work with mobile phones as a headset and in fact includes a high performance microphone, a single retractable earbud, and CSR BlueCore5 Bluetooth technology. The Mobile 2 also boasts two 25mm high-fidelity speakers whose volume can be turned up high enough to allow the unit to serve as a highly portable speaker system. Essentially, the Audio Mobile 2 can either be used as a ‘public’ listening device via the speakers or as a private ‘headset’ via the earbuds. In addition, the Mobile 2 boasts an internal audio amplifier that delivers rich bass and clear/crisp middle & high range sound, dual flex points that enables users to customize their fit without sacrificing the unit’s unique style, an on-board volume control, mute and multiple music play/forward functions, and a send/end call button. It should also be noted that the Mobile 2 is powered by a rechargeable Lithium Polymer battery and in fact comes equipped with a USB charging cable and a wall adapter. The S1 Audio Mobile 2 retails for a slightly more expensive $159.95 (versus $129.95) and comes with a 90 day limited warranty.