¡ì pinhole into the audio port ¡ì circular volume with fixed supports ¡ì can be concealed installation ¡ì dedicated preamplifier IC ¡ì high sensitivity listen ¡ì low noise, low distortion ¡ì power polarity protection circuit
50 to 80 m2 Impedance 600 ohms Frequency of 200 ~ 10Khz Power supply 6 ~ 14VDC Size 13 * 50mm For Kang, Dahua DVR device