The Siemens SENTRON 5SU9306-0KK06 is an RCBO — a combined residual-current device and miniature circuit breaker in one 18 mm wide unit, 1P+N, rated 6 A with a 30 mA residual trip and Type B tripping characteristic. The 70 mm installation depth and 77 mm overall depth keep it clear of the gland plate in a standard 125 mm tall enclosure.
The 6 A rated current at 30 °C is the continuous load it can carry in a 30 °C ambient — at 40 °C that derates to 5.64 A, at 50 °C to 5.22 A, and at 55 °C to 4.86 A. So if the panel sits in a hot machine cabinet, size the load accordingly.