Eathtek Replacement Motorcycle Helmet Stereo Headset Speakers With Mic Microphone For MP3 MP4 IPHONE IPOD GPS Cell Phones for iPhone, MP3, Phone, other Music Device Earphone diameter: 3.7cm Earphone/MIC sensitivity:-58Ddb3db Earphone impedance: 3215% All pictures are taken from the real item, please check carefully before bidding.