You will get: 2 pack door stoppers (battery is not included) 3 levels of sensitivity: L-low sensitivity, M-medium sensitivity, H-high sensitivity, you can adjust the sensitivity according to your needs choose Loud alarm: 120dB loud alarm is easy to hear and the synthetic rubber on the bottom prevents slipping and floor damage No installation required: install one 9V battery, turn the knob to ON and it works. When it is off, it can be a door stopper without an alarm. The distance between the door and the floor should be 10mm (0.38 inch) to 35mm (1.35 inch). If the gap is more than 35mm, please put a soft material under the door stopper Lightweight and compact: length - 14cm, width - 4.5cm, height - 4cm, 98 grams per stopper , comfortable to wear