Use the DOOR STOP ALARM as an entry alarm and to block a door from being opened. If anyone tries to open the door, this 120dB alarm will sound. Alarm stops when pressure is released from door stop plate. There is also a movement sensor that will activate the alarm if it’s tampered with. On/off switch is on the back of the alarm and includes a low battery indicator light. Uses one 9-volt battery (not included). Measurements 6 3/8″ x 1 3/4″