It's built as a UL 1077 supplemental protector for 277 V AC circuits, with a 6 kA interrupting capacity. The K-curve means it trips between 8x and 12x rated current — designed for inductive loads like motors and transformers where inrush won't nuisance-trip a standard C-curve, but you still want short-circuit protection downstream of a branch-circuit OCPD.
Compared to the C-curve siblings (S202M-C10, C16, C20), the K-curve on this unit shifts the magnetic trip threshold higher — 8–12x vs 5–10x for C-curve. That's the difference between holding through a motor start and nuisance-tripping. Same 2-pole DIN-rail footprint, same 6 kA interrupting rating at 277 V AC. If your BOM calls for a C-curve and you're swapping to K, verify the downstream device's let-through energy still coordinates.
Two-pole width (roughly 36 mm) fits a standard 12-module panel row with room for six units. Rated 277 V AC phase-to-neutral or 480Y/277 V three-phase — the 6 kA interrupting rating is sufficient for most supplemental protection applications downstream of a branch-circuit breaker. Terminal torque and strip length per the manufacturer's installation instructions on the unit label.