The Glass Breakage Alarm is an effective low cost vibration alarm  can be used for securing windows or doors if someone tries to break through. Installs easily on any window. It can also be used as a personal property alarm to protect computers, TVs, etc.  Includes one 12 volt battery and strong adhesive tape.  Turn the switch on the side to the ON position.  When the glass is hit knocked or broken by anyone or anything, the siren will sound for approximately 30 seconds before it shuts off and resets.