The SIEMENS 3RV2901-1D is a compact auxiliary contact block designed for use with 3RV2 motor protection circuit breakers in sizes S00 to S3. It provides a single changeover (1CO) contact configuration and is mounted directly on the breaker for space-saving installation. This accessory ensures reliable signaling and status indication, supporting flexible integration into control circuits. Engineered for durability and precision, it enhances the functionality of motor starter assemblies by offering consistent auxiliary switching performance.