Infrared Induction Doorbell Transmitter + Receiver Set - White (2 x AA)
Receiver working voltage: DC 3V; Transmitter working voltage: DC 9V; Transmitting frequency: 315MHz; Transmitting distance: 150m(Open field without obstacles and interference the receiver and the transmitter should be used in the same floor transmission distance is about 10m when there are two walls between them); Infrared induction distance: 3~7m.