Wireless Microphone, Karaoke Microphone, UHF Wireless Microphone, Professional Microphone, Mic, Wireless Mic, PA Mic Wireless Microphone, Karaoke Wireless Microphone, UHF Wireless Microphone, Professional Microphone, Mic, Wireless Mic, PA Mic, Karaoke MicrophoneModel: K ... components and technics * AA size batteries for microphone, supply time up to 10~30h * Dual DC-DC step up circuit design for ...