The Homematic IP window and door contact is part of the Homematic IP smart home system and reliably monitors doors and windows. The innovative sensor does not rely on conventional magnetic contacts but instead uses a sophisticated optical sensor. This eliminates the need for an additional magnet, reducing installation effort. The built-in infrared light barrier monitors the door or window and detects whether it is open or closed. Within the Homematic IP system, the small sensor performs multiple tasks. Firstly, it automatically reduces the heat supply during ventilation by informing the Homematic IP radiator thermostat as soon as a window or external door is opened. Particularly practical is the option to define a reporting delay for frequently used doors to avoid constant opening and closing of the radiator valves. Secondly, the sensor reliably monitors access to your home when you are away. When the alarm mode is activated, the Homematic IP siren can be triggered in the event of unauthorized window opening. Additionally, a warning notification in the form of a push message is sent to the user via the app, allowing them to respond promptly to the dangerous situation. The small, 30-gram sensor operates so efficiently that it can run on a single AAA battery for about two years. When the battery capacity is low, the Homematic IP app will notify the user. Its lightweight design allows for reliable attachment using double-sided tape, which comes with an additional brown cover cap and a reflector foil. If the window or door material does not permit tape attachment, the two tiny screws included can be used instead.