This compact, easy to install magnetic contact alarm made by Intermatic (a recognized leader in the security industry) can be used on doors, windows- anything that opens and closes. It is an ideal security device for home, store, office, etc. If the protected door or window is opened it will sound a powerful 110dB alarm to scare off the intruder and alert you to the attempted entry. The owner can arm or disarm the unit using a programmable security code. For added protection one window security sticker is included. It has a 30 second exit delay and a 10 second entry delay. It requires 4 AA batteries that are not included. A low battery indicator will inform you when it is time to change the batteries. The dimensions of the alarm are five and three-eights by two and three-quarters by one and one-quarter inches.