This alarm is perfect for glass windows, doors, and RV's. The alarm has a piercing 120-decibel siren that is activated when vibration, shock, or glass breakage is detected. The alarm can be armed and disarmed by using a special key. Features: can be attached to any flat surface for protection; warning sign as a theft deterrent; selection switch for 30 - 40 sec. siren cycle is selected; no wiring or installation required; low battery indicator; battery included.