... per Inner box:12 Features Specification: super door stop alarmThe door wedge alarm is for indoor use only. ... * Insert the alarm at the base of your door, making sure theNon-skid pad on the bottom ... in firm contactWith the floor. * When the door is opened, the alarm's metal plate is depressed ... switch. * Use a 9V battery, not included* The door alarm gives great protection for home, office, orMotel room ...