The Door Stop Alarm is designed in the shape of a 6” long door wedge. Simply place it behind any door. When the door is opened it will jam the door and at the same time gives off a loud, shrill, pulsating alarm. It is designed to scare away intruders instantly. This is a completely self-contained, easy to carry and easy to test unit. Providing great protection for home, office or motel when traveling. 118 dB alarm, anti-slide sole plate, uses one 9 volt battery (sold separately). Size: 6” x 2” x 2-1/4” Door Stop Alarm - #SDS