PoolGuard's Door Alarm DAPT-WT can help protect any swinging or patio door near a pool. When a child opens the door the alarm will sound immediately, and will continue to sound if the door is left open. If a child goes through the door and closes it, the alarm will sound for 5 minutes and then automatically reset. It is equipped with an Outdoor Wireless Transmitter that allows adults to enter the home from the outside without the alarm sounding. Alarm also is equipped with an adult pass through feature that will allow adults to go through the door without the alarm sounding. It is always on and will automatically reset if tripped. Uses one 9 volt battery (not included. Comes with wireless transmitter, sensors, sensor magnet, hookup wire, screws and anchors.