B-curve at 4 A means the magnetic trip fires between 3x and 5x rated current (12–20 A). That's tight enough to protect sensitive DC loads — control power supplies, relay coils, electronic modules — while riding out the inrush of a small DC-DC converter or a contactor pickup. The 2-pole construction switches both lines in a DC circuit, which is required for full isolation on ungrounded or floating DC systems. The 95% humidity rating at 55 °C (derating to 35% at 75 °C) means it's fine for non-condensing environments like a ventilated electrical room — not for direct washdown zones.
Screw terminals accept 0.75 to 35 mm² solid or stranded copper, torqued to 2.5–3.5 N·m (22–31 lbf·in). Combined top and bottom terminals let you daisy-chain busbars without extra jumpers. IP20 with conductors connected — fine for enclosed panels, not for exposed outdoor mounting without a secondary enclosure.