It carries 220 kA interrupting capacity at 240 V, dropping to 154 kA at 415 V and 75.6 kA at 440 V — numbers that tell you this breaker is built for high-fault utility or transformer-fed distribution, not light branch protection.
Rated 125 A from 40 °C through 50 °C, then derates to 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. Dimensions are 130 mm high × 76.2 mm wide × 70 mm deep, with IP40 on the front face. That 70 mm depth is shallow enough for most 600 mm deep enclosures; the 3-pole width of 76.2 mm (3 inches) is standard for this frame class. Max power loss is 28.1 W — factor that into your thermal budget if grouping several breakers.