MSRP $ 8.95

The "worlds smallest window alarm" protects your home or business from thieves. This unit uses a magnetic sensor to detect the opening of a protected window. An alarm will then alert you to an attempted entry and scare off potential intruders.
The owner may open the window or other protected object, without setting off the alarm by inserting a deactivation key. Once the deactivation key has been removed and the protected door or window is opened, the alarm will sound until the key is inserted or the door or window is closed.
Inconspicuous alarm for showcases, cash registers, gun cabinets, medicine cabinets, or sliding doors. With it's low price, you can easily afford as many as you need.