The Siemens 5SL6105-7YA is a 1-pole miniature circuit breaker (MCB) with a C-trip curve, rated 0.5 A at 230/400 V AC and a 6 kA breaking capacity. This is the part for protecting a very low-current branch — think control transformers, signal conditioners, or PLC power supply feeds — where a standard 1 A or 2 A MCB would be too coarse to clear a fault before the downstream device fails.
At 0.5 A, this is an uncommon low rating; verify that the downstream load's full-load current does not exceed 0.5 A and that the minimum fault current at the panel location exceeds the magnetic trip threshold (roughly 2.5 A to 5 A) to ensure the breaker clears a hard short within its instantaneous trip band.
The 1-pole width (roughly 18 mm per module) leaves room for adjacent poles or a neutral busbar. Wire termination accepts up to 25 mm² conductor for the line and load sides.