The Blaupunkt DC-S1 is an extension of your Blaupunkt SA and Q alarm system. The window / door sensor works on a 3V battery so you can attach the sensor to any desired location. As soon as the sensor is connected to the main panel, it signals a detection. A detection takes place when the 2 parts of the sensor come apart. Via the main panel you will then receive a message on your smartphone (iOS and Android). In addition, the alarm goes off at home. So everyone is aware that there is danger in your home.