The door alarm will sound in 7 seconds when a child opens the door and the alarm will continue to sound until an adult comes to the door and resets the alarm. poolguard door alarm will sound in 7 seconds even if a child goes through the door and closes it behind them. the door alarm is always on and will automatically reset under all conditions. poolguard door alarm is equipped with an adult pass through feature that will allow adults to go through the door without the alarm sounding. optional screen door kits can be purchased for the alarm, this kit allows you to get air through your screen door without the alarm sounding. poolguard door alarm uses one 9-volt battery, (not included) with a battery life of approximately 1 year. the door alarm is equipped with a low battery indicator that will audibly alert you when your battery is getting low. poolguard is the only door alarm that is ul listed under ul 2017 for water hazard entrance alarm equipment.