Waterproof door opening/closing sensor that notifies people in and out of people; Battery operated, so you can install it anywhere (Magnetic Sensor Batteries: 12 V 23 A). When you attach it to your entrance or store to notify you of people when you receive radio waves from the receiver transmitter, which is useful for crime prevention and family care. The sound and light notifies you from 555 kinds of sounds can adjust the sound to 1110 sounds to 10 sounds to 10 dB. 100 m (100 m) Transmission distance and speed varies depending on building structure, obstacles, usage environment, etc.It can be used in rooms with 1 detached or large apartments.Can be used in small, medium sized stores, offices, apartments, offices, private rooms, etc.