This is a mini outdoor Microphone with listening ranges 10 m² to 50 m². Adopting Hi-Fi and low-noise chip, it cam effectively restrain ambient noise by frequency-selecting repeatedly. It has clear and clean voice, build-in lightning protection and reverse polarity protection. It is suitable for bank, prison, market, industry, exam room, etc. With the advantage of low noise, high fidelity, wide voltage, low power consumption and far transmitting range. It is the ideal product for CCTV security system and can realize video and audio synchronization by working with camera.