1)Alnico protection shell, deluxe design.2)Code number keyboard, automatically backlit button at night time.3)Unlock set by dwellers, independent password, installed freely.4)Reset valid dwellers, limit invalid dwellers.5)Display talking-time by reverse time.6)Easy installation, the outstation adopted 4-cord and 1 video wires.7)Infra-red at night time.8)Timely switching-off while monitoring and talking. B/W Code Video Door Phone Syst