That 125 A holds flat from 40 °C through 50 °C ambient, then derates to 120 A at 55 °C, 117.5 A at 60 °C, 115 A at 65 °C, and 112.5 A at 70 °C — so in a warm enclosure you lose about 10 % of headroom at the top end. At 240 V it interrupts 121 kA; at 415 V, 75.6 kA; at 440 V, 52.5 kA; and at 690 V, 11.9 kA.
Dimensions are 130 mm height, 76.2 mm width, 70 mm depth — a standard 3-pole MCCB footprint that drops into a SENTRON distribution panel or a DIN-rail adapter. That saves a wiring step versus adding a separate alarm module later.