This device is a smart sensor that can be installed on doors and windows. The built-in sensor detects vibration and emits a 120 dB alarm to alert you of a potential break-in and scare away burglars. It has a unique high/low sensor sensitivity setting, to helps prevent false alarms. The red warning LED light blinks every 4 seconds, to caution would-be intruder of the window’s protection. Comes with warning sticker, stick on windows to scare away burglars. The low battery warning, remind that you need to replace the battery, will not miss the safety protection at home. Requires AAA*2pcs batteries (not included), AAA batteries give these alarms great battery life, you don't have to change often. No wiring is needed, simply peel and stick the alarm on any window or glass. Perfect for any window (including sliding windows) in your home, garage, office, RV, dorm room.