Pinhole Style Microphone,Omni Directional, Monitor Range 10-30sq.m,suit for prison,jail room,small ... room,very secretly Pinhole Style Microphone,Omni Directional, Monitor Range 10-30sq.m,Size 60mm*22mm, Weight 30g, White ... 60mm × 22mmWeight 30gStandard CE I.TRADIO hidden,mini,built-in wall Audio Surveillance Microphone