The built-in/surface-mounted opening detector is a magnetic contact that you can use to secure doors and windows. Unauthorized opening is detected and reported to the alarm center. The built-in/surface-mounted opening detector consists of a magnetic contact (reed) and a magnet. These are installed either parallel, face-to-face or orthogonally to each other - at a distance of at least 8 mm. The circuit of this NC opening detector is closed when idle. If the distance between the reed and the magnet increases, the circuit is interrupted and an alarm is reported. The detector is sabotage-proof and protected against external fields. External field protection means that only the magnet that belongs to this opening detector has the right field strength to keep the circuit closed. Any change in the field strength (e.g. due to an external magnet) interrupts the circuit and an alarm is reported. The optimal installation location is the middle of your door or window frame. Installation on the lower window frame is also possible if a certain window is to be tilted with a secured magnetic contact. The detector is suitable for both surface and flush mounting. It is waterproof and dustproof (IP 68). The opening detector is VdS certified and available in white and brown.