... 2.4 G Frequency-Hopping Spread Spectrum technology afford stable digital signal transfer;5. Adaptive frequency hopping, Strong anti-interference ... OSD menu, Menu Language: Chinese, English;8. built-in 16 doorbell chime;9. Wide angle lens and IR night version camera, ... in dark enviroment;10. Calling out, surveillance, unlock door, talking and door bell etc. function;11. Suitable for single house, ...