The A9P64720 is a 20 A, D-curve miniature circuit-breaker (MCB) from Schneider Electric's Acti9 iC40N series. The 3P+N configuration protects three phases and switches the neutral; the neutral pole is not internally protected, so it's a switched neutral, not a 4-pole protected breaker. That matters when you're wiring a three-phase distribution board and need a single neutral bar downstream. Breaking capacity is dual-rated: 10 kA Icu at 400 V AC per EN/IEC 60947-2 (the industrial standard for fault-clearing ability) and 6000 A Icn at 400 V AC per EN/IEC 60898-1 (the household/residential standard). The 20000-cycle electrical and mechanical endurance tells you it's built for regular switching in a distribution board, not a one-time-only backup.
Clip-on DIN rail mounting, 6 modules wide at 9 mm pitch (54 mm total width). Terminals accept 1–16 mm² rigid or 1–10 mm² flexible copper; strip 14 mm and torque to 2 N·m.