Audio Only Sub Station - The JK-1SD is an audio only Sub Station that can be connected in place of the sub monitor in the JK series system. The unit features a TALK button to activate the VOX or PTT style communication, separate off button, a call tone volume and receive volume control, a call button to call master, and a button for door release. The JK series offers a 170° camera view and gives the user the ability PanTilt and Zoom the camera to a desired area for a better view of the visitor. The JK series offers a backlight/night sensitivity adjustment. In low light (night time) and heavy background light (sunny day) situations, the user can press the ADJUST button to improve the image quality to aid them in identifying the visitor. The JK-1SD audio sub can talk to and release the door station as well as call the other inside monitor station.