The Doberman magnetic Window/Door Alarm is a sleekly designed unit enabling it to function with many sliding glass windows and doors. The magnetic Window/Door Alarm is triggered by both window vibration and entry opening. Place the included magnet on the outside frame of any window or door you wish to protect. When opened by an intruder, the magnetic circuit is broken and a loud alarm will sound. The alarm unit will also sound when window vibration is detected. Printed on the reverse side of this product is a red warning label that can be seen outside through the window. It notes that your property is protected by Doberman and deters potential burglars.