The door stopper alarm need battery-operated that it s requires 1 X 9V battery (package not included) Package: 1X Door Stopper Alarm (without battery), 1 X portable door lock. Why do we need to have Dual Protection Security Door Kit? Are you worried about the insecurity in a hotel and fear of strangers opening your room? So, imagine, you re alone at home or in a hotel or airbnb room or rentals, sometimes the door lock does not work efficiently. Don't worry, if you have Our Security Door Kit, it will prevent unauthorized entry, provide absolute security and privacy of your room and peace of mind in those situations. Notes: 1. Place it under the door, the gap between the bottom of the door and the floor should be 10MM(0.38 in) to 30MM(1.35 in). 2. Smooth floor can try to use H-type sensitivity, vibration-sensing alarm. 3. When the alarm sound gradually becomes smaller, it means to replace the new battery. 4. Turn off the power supply can be used as a doorstop. 5.Heavy Duty Travel Door Lock has two different sizes of locking holes: 0.78 inches fitting normal doors, 1.2 inches fitting doors with larger bolts, it might doesn t work on all door, please chick out the size of your door before buy it(you can chick the size in the picture 2) 6.portable add lock can only be used for in-swinging hinged door.