The Siemens 5SY6305-8 is a SENTRON miniature circuit breaker — 3-pole, D-curve, rated 0.5 A at 400 V AC. Breaking capacity is 6 kA per EN 60898 for general-distribution duty, and 30 kA per IEC 60947-2 for industrial panel coordination — that 30 kA figure is the one that matters when you're sizing upstream protection in a high-fault plant environment.
Mounting position any, so it works in horizontal busbar drops or vertical panel layouts. IP20 with conductors connected; sealable cover option available if the panel spec requires it. Halogen-free and silicon-free construction, which matters for clean-room or food-bev lines where outgassing contaminates product.