It's a 3-pole device rated 0.4 A operational current at AC-3 duty on 400 V, with a magnetic instantaneous short-circuit trip set at 5.2 A. That trip point is what matters: it's sized to protect a motor branch against a bolted fault without nuisance-tripping on inrush. That means it drops into a standard panel without adapters — the S00 footprint is common across the SIRIUS breaker range, so swapping within the family is a straight rail slide.
The headline number is 0.4 A at AC-3 400 V — that's the motor-switching current, not the thermal continuous rating. AC-3 covers starting and plugging of squirrel-cage motors, so this breaker is for the smallest motor branches: fractional-horsepower pumps, small fans, valve actuators. The magnetic trip at 5.2 A (13× the AC-3 rating) clears short-circuits fast but won't pop on a normal start. Ambient range is -20 to +60 °C operating, -50 to +80 °C transport; relative humidity 10 to 95 %. Shock rated at 25 g / 11 ms per IEC 60068-2-27, so it survives shipping and panel vibration on a conveyor line. Terminals accept 2×(0.75…2.5 mm²) solid/stranded or 2×4 mm², with screw torque 0.8…1.2 N·m. AWG equivalent 2×(18 to 12) for main contacts. That's standard for S00 — no special crimp tools needed, but use ferrules on stranded for a clean connection.
Size S00: 45 mm wide, 97 mm tall, 96 mm deep. Clearance requirements: 50 mm above and below, 30 mm to the side, 0 mm forward/backward. That's tight — you can butt it against the backplane or enclosure door.