... are optional 3.5/4-inch color LCD With the function of video talk-back, unlocking by remote control, monitoring Door-stationIn case ... station, withdraw a garrison and Arming in the defense area3.5/4-inch color Liquid Crystal Display, Easy viewingHands-free calls ... : 15,625±400HZ V: 47±3HZ Display color TFT: 3.5/4inchMaterial of frameABS Color hands-free door entry 3.5",4"TFT kit "L"