The Siemens SENTRON 5SY4105-8CC is a 1-pole miniature circuit breaker with a D tripping characteristic, rated for 0.5 A at 400 V AC. It breaks faults up to 10 kA per EN 60898 and 5 kA per UL 1077 / CSA C22.2 No. 235, so it handles both IEC and North American panel specs without a separate part number for each market. The D-curve means it tolerates short-duration inrush up to 10–20× rated current before tripping magnetically — sized for motor-starting or transformer loads where a C-curve would nuisance-trip. At 0.5 A, this is a control-circuit or small-signal protector, not a branch-circuit main.
Depth is 76 mm with 70 mm installation depth, so it clears shallow enclosures.