The ABB S201-C20NA is a 1-pole + neutral miniature circuit breaker from the System pro M compact series, rated 20 A with Trip Curve C and a 277 VAC maximum voltage. Snaps onto standard DIN rail, so it integrates directly into an existing panel layout without adapter plates or special mounting hardware.
That suits loads with moderate inrush — think small motors, transformers, or banks of LED drivers — where a Curve B would nuisance-trip on startup but a Curve D would let a sustained fault ride through too long. The 20 A rating is the continuous thermal current at 30 °C ambient. The 1-pole + neutral form factor switches the phase only; the neutral bar is solid through the breaker.