Plantronics MX203S-X1S Stereo Mobile Headset for most MP3 Enabled Mobile Phones For most Stereo phones with 2.5mm headset jack and call/answer end function, not compatible with Treo Smartphones Take calls, listen to stereo music on your MP3-enabled phone Be heard clearly with WindSmart microphone Unparalleled comfort with unique Flex Grip design Conveniently located one-touch call answer/end