You don't need to install a full alarm system to maintain security at an entrance. The 105dB Door/Window Alarm is a standalone, battery-operated unit that emits an ultra-loud 105 dB alarm in the event the monitored entrance is breached. No wiring or electricity is required: The 105dB Door/Window Alarm runs on 3 LR44 button cell batteries, which come pre-installed on the unit. The 105dB Door/Window Alarm is easy to install and use. Position the alarm on the stationary edge of the door or window frame and mount it to the frame using the included double-sided, pressure-sensitive tape. Mount the magnet at the edge of the door or window so that the magnet and the alarm arrows align with each other. The alarm sounds when the magnetic contact is separated. A key is included that arms and disarms the unit. Use the 105dB Door/Window Alarm to keep an eye on doors, windows, sliding glass doors, or even a potentially dangerous cabinet or closet. If the entrance you wish to monitor is outside, such as a gate or outer door, install the Weatherproof 105dB Door/Window Alarm instead.