Sub Monitor Station - The JF-2HD is the sub monitor for the JF expanded series hands-free color video series. The unit connects to a master JF-2MD and an additional JF-2HD sub monitor (or JF-2SD audio only sub). The unit features a 3-1/2" TFT color monitor, a TALK button for PTT or VOX activate communication, a door release button, call-in LED's, door chime and communication volume controls and brightness control.