Expands the built-in audio module by an additional 12 binary inputs. For integration into mailboxes and doorbell systems from various manufacturers, for example in products from Erwin Renz Metallwarenfabrik GmbH & Co KG, Boschstr. 3, 71737 Kirchberg/Murr. With interface for connecting additional built-in button extensions. The built-in audio module can be expanded to a maximum of 99 inputs for doorbell buttons using the built-in button extension. Consumption units: 1 Suitable for use with the camera interface (83327), the 180° camera module (83503) and the status module (83190). Further information on commissioning and operation can be found in the system manual and the online operating manual.