The Siemens 5SJ6306-7RC is a 3-pole miniature circuit breaker from the Retail line, rated 6 A with a C characteristic and a 6 kA breaking capacity.
At 6 A it protects a 1.5 mm² copper conductor under typical installation rules. The 6 kA breaking capacity at 230/400 V is adequate for most commercial sub-distribution where the prospective short-circuit current stays under that level; verify the SCCR at the point of installation for coordination with the upstream device.