Rated protection for a single-phase final circuit
The Siemens 5SU1354-1LV20 is a combined residual-current device and miniature circuit breaker (RCBO) — an FI/LS protector — in a 1+N-pole form factor.
Where this fits in the panel
The 70 mm depth (D=70MM) keeps it within the envelope of most domestic and light-commercial consumer units. The 1+N-pole format switches the line conductor and switches/isolates the neutral, which is the common arrangement for single-phase final circuits in TN and TT earthing systems.