The Goldammer AM-GB-202F NRA 25RS/DN50 is a level controller for external mounting on tanks (AM series), specifically the wall-mounted version, identified by the designation "202F," which indicates a particular model, often with 25 RS (relay switching output) and DN50 (50 mm diameter connection/flange). It is used for the precise control and regulation of liquid levels directly on the tank wall, ideal for applications where an internal level sensor is not possible or desired, and features a reliable switching function.