The ABB S201-D40 is a 1-pole miniature circuit breaker rated 40 A with Trip Curve D, meaning it's designed for loads with high inrush currents — motor starters, transformers, or solenoid banks — where the magnetic trip threshold (10–20× In) prevents nuisance tripping on startup. Rated 277 VAC line-to-neutral (or 480 Y/277 VAC three-phase), it covers common North American panel voltages. The DIN-rail footprint snaps into standard 35 mm rail — no adapter needed, and the finger-safe terminals accept stranded or solid copper without ring lugs. Listed as UL 1077 supplementary protector and CSA 22.2 No. 235, so it's recognized for use within an end-use equipment enclosure — not as a service-entrance disconnect, but as branch-circuit protection inside a control panel or machine. That distinction matters when the inspector reads the nameplate.
The UL/CSA listing means compliance documentation (RoHS, REACH, UL file) is standard with the shipment.