This compact adapter transforms your Audio-Technica headphones into a mobile headset for your music phone. The AT-MP100 adds a professional-quality microphone, as well as a convenient volume adjuster and control button to your 3.5 mm stereo headphones, allowing you to answer and end calls on your iPhone(TM) or Palm(R) Treo(TM) smartphone. Use the control button to switch between phone calls and music, as well as play, advance and pause songs on your iPhone.