The 125 A rating holds flat from 40 °C to 50 °C, then derates to 114 A at 70 °C — that's a solid thermal curve for a crowded enclosure. Interrupting capacity hits 75.6 kA at 240 V, 52.5 kA at 415 V, and 11.9 kA at 690 V. Power loss maxes at 30.6 W, so factor that into enclosure heat calculations.
Dimensions are 130 mm high, 76.2 mm wide, 70 mm deep — standard 3-pole MCCB footprint for a SENTRON panel. The UVR is the design-of-auxiliary-release type, so verify your control circuit voltage matches the release coil rating before wiring.