Specs that govern the fit
The 6 kA interrupting rating at 277 VAC and 10 kA at 250 VDC give it the breaking capacity for industrial panel branch circuits, not just residential lighting.
Single-pole width means it occupies one module slot — 17.5 mm — so it fits tight sub-distribution boards and leaves room for auxiliary contacts or surge arrestors in the same row. No special panel cut-out needed; it clips in and out with a screwdriver on the release tab.
The 277 VAC rating covers 277/480 V wye systems common in North American commercial and light industrial panels — the breaker clears faults on a 277 V line-to-neutral circuit. The 250 VDC rating suits DC bus or battery-backed control circuits; the 10 kA DC interrupting capacity is notably higher than the AC figure, reflecting the harder arc-extinction challenge on DC. Both ratings are per IEC 60947-2 and UL 1077 (supplementary protector) where applicable.