Outdoor Unit - Rated Voltage: DC 9V (from household unit); Wiring: 2 wires ( non-polarity); Communication: Simultaneous communication; Distance: 0.5 : 28m / 0.65 : 50m; Doorphone - Power source: AC 110/120/220/230/240V,50-60Hz; Output power(Audio): 70mW; Output power(Call): H : 400mW L : 100mW; Effective Distance: Room-Room : 30m/0.65 Ø Room-Door : 50m/0.65 Øen