Interrupting capacity — the real-world number
That 121 kA at 240 V is the headline, but the more relevant figure for most industrial panels is 75.6 kA at 415 V and 52.5 kA at 440 V. If your service entrance or downstream fault current is north of 50 kA, this breaker handles it without cascading upstream.
Thermal derating — don't ignore it
At 55 °C it drops to 31 A, and at 65–70 °C it's 30 A. If you're packing this breaker into a hot enclosure or next to transformers, plan for that 2 A derate. The TM210 release is factory-set; no field adjustment.
Footprint is 76.2 mm wide, 130 mm tall, 70 mm deep — that's a standard 3-pole MCCB slot on a DIN rail or panel-mount adapter.