SAF-ALARM-WEDGE Portable Door Wedge and Door Stop AlarmUse this 120 dB Door Stop Alarm to block a door from being opened. if anyone tries to open the door, the alarm sounds. There is also a movement sensor with adjustable sensitivity to activate the alarm if tampered with. An on/off switch allows the alarm to be turned off so that it doesn't go off in your luggage. Uses one 9-volt alkaline battery (not included).