Motor-protection breaker with magnetic-only trip
That is a serious interrupting rating for a 50 A frame; you are buying coordination headroom, not just a switch.
The MA trip unit is magnetic-only — no thermal bimetal. That is intentional: motor feeders typically have a separate overload relay set to the motor FLA, so you want the breaker to ride through starting inrush and only clear on a bolted fault. The 100 kA Icu at 690 V AC is the maximum short-circuit current the breaker can interrupt once and still be serviceable (Ics is typically 50% or 75% of Icu on this class — the spec table does not give Ics here, so assume 50 kA for repeated duty).
The 3-pole unit is 105 mm wide, 161 mm tall, 86 mm deep — fits standard panel cutouts for the NSX100HB2 frame. IP40 enclosure protection means it is suitable for clean indoor panels but not washdown areas. IK07 impact resistance handles incidental tool contact during commissioning.
Electrical durability depends on load: 20,000 cycles at 440 V at half rated current, 10,000 cycles at full rated current at 440 V, and 5,000 cycles at 690 V at full current. For a motor-starting application where the breaker sees infrequent fault clearing but regular switching via a contactor, the mechanical life is the limiting factor — expect the contactor to wear out first.