Features:

1.Surface mounted, supported up to 4 monitors & 2 doorbell/cameras
2.Clear and bright image with 4 inch flat TFT or CRT Monitor and doorbell/camera
3.Hands-free monitoring video & audio of door
4.Intercom between monitors
5.With infrared LED illuminator
6.Door release
7.Brightness/contrast adjustable
8.Ring volume adjustable