Security home/window alarms ~Senses door movement ~Disturbing sound ~1.5 year battery life ~Easy stick ~0771691444 Cost 10usd,How it works A door and window alarm sensor works by using a sensor and a magnet. The sensor is placed on or inside the door or window frame. The magnet is placed on or inside the door or window itself. When the door or window is opened, the magnet will separate from the sensor, causing it to activate.,To see video on how it works app 0771691444
$10