The Metro.fi 150v has all the great features of the Metro.fi 150 but also features integrated voice functionality and is specifically designed for use with the iPhone (and other mobile music phones with the same headset jack). A miniature high performance microphone allows for hands free phone calls. An in-line multi-function button answers and ends calls and controls music/video on your iPhone. The Metro.fi 150v has excellent acoustic speaker technology, making it the best single value in-ear speaker product on the market at this price point. The Metro.fi 150v's comfortable in-ear design provides noise isolation that reduces ambient interference and enhances quality of sound. The body has a small and lightweight yet durable form factor for the active lifestyle. Accessories include three single flange silicone ear tip sizes: small, medium and large, and one set of dual flange silicone ear tips along with a pocket ready hard carrying case. Product specifications are single, high performance, dynamic speaker, 106 dB SPL/mW at 1kHz input sensitivity, 16 Ohms nominal impedance, 46 inch cable length, 1/8 inch (3.5mm) gold plated stereo plug, 20 Hz-20,000 Hz frequency response, and 16 dB of noise isolation with omni-directional microphone with -40dBV/Pa at 1 kHz sensitivity.