Bi-directional sensor for securing windows and doors against forcing / levering open. The most important sensor for securing the building envelope. Windows and doors are the greatest weak points in the outermost layer of your residential unit. Regardless of the property to be secured (house, flat, garden shed, garage, business, office or warehouse), it is advisable to secure all windows and doors with sensors. If a window or door is broken into, the door/window sensor triggers an alarm in the alarm system. The burglar is not yet in your living area at this time. If a loud external siren has been installed, the risk of the burglar being caught increases enormously. The sensitive magnetic contacts immediately trigger an alarm if they are opened in the alarm state. However, the alarm triggering can also be delayed (e.g. for the entrance door). You can tilt the windows without triggering an alarm in the alarm system. Open windows will be signalled when activated.