Fortress Security Store Wireless WiFi Camera Battery Discrete Contact Sensor for Home Security Alarm System - Window & Door Contact Sensors for DIY Home Alarm System

The most likely method of forced entry into a home or office is via a door or window. That's why it's so important to have contact sensors attached to the windows and doors on your home - at least on the ground floor. These magnetic sensors can detect any time a window or door is opened. If the alarm is armed, it'll be triggered - setting off the siren system will call a sequence of designated numbers until someone picks up.