... electronic noise.*High sensitivity, low noise.*Restraining high intensity voice automatically, protecting rear devices*Echo-concelling appearance design, ... directly drive DVR, VCR, headphone, loudspeaker etc.*Excellent voice experience, widely working temperature: -25~75°C*According with ... PVCSize 60mm × 22mmWeight 30gStandard CE I.TRADIO hidden,mini,built-in wall Audio Surveillance Microphone