Curve B means it trips between 3x and 5x rated current — typically used for resistive or general-purpose loads where inrush stays low, such as lighting circuits, control transformers, or small heating elements. The 2-pole configuration switches both line and neutral in single-phase AC circuits, or two poles in DC applications. Rated 277 V AC and 500 V DC, with interrupting capacities of 6 kA at 277 V AC and 10 kA at 500 V DC.
For a 25 A circuit, verify that the upstream feeder and busbar are rated for the full load — the breaker itself is the protection device, not a load-carrying bus. In a crowded enclosure, allow finger space for the toggle and terminal access; the S200MUC footprint is consistent across the series, so swapping curves or ratings later uses the same DIN space.