YIHAO Mic Microphone Car Radio CD Player Stereos Bluetooth FOR Kenwood KMM-BT312U WITH HOLDER Standard Operation Voltage: 4.5V Operation Voltage: 1.0V-10V.DC Wire Length: 4 M Adopting humanity design with U shape fixing clip , is more easy to install and reliable. it's highly improved the speech quality of hand free car kit communication system. with fast and accurate data transmission, which could guarantee the voice clearly and stably under kinds driving occasions,