Handsfree talkback function. Electronic control lock function. Indoor mutual talkback function. Brightness, color and sound volume of indoor phone can be adjusted. Outdoor station is exquisite and durable; it has function of viewing at night by infrared. The available distance is 200M to connect the connection wire; he guide line with 4X0.75MM square meter can be used. it will not affect the picture it shows and talkback. Specifications: Indoor Monitor: Screen size: 7"(16:9 display) Resolution: digital: 800*(RGB)*480 Visual angle: up 50 degree, down 70 degree, left or right 70 degree Brightness: 200cd/? Ringtone: chorded polyphonic ringtone Sensitivity: 56db Signal system: PAL/NTSC (optional) Overall Power Consumption: =6W(400mA) Stand-by Power Consumption: