It carries a breaking capacity of 75.6 kA at 240 V AC, 52.5 kA at 415 V, 32 kA at 440 V, and 11.9 kA at 500 V and 690 V — figures that tell you the available fault current this breaker can safely interrupt at each voltage level.
The 40 A rating holds across 40 °C to 50 °C ambient, then derates to 39 A at 55–60 °C and 38 A at 65 °C, 37 A at 70 °C. If your panel runs hot (enclosed, stacked breakers), use the 55 °C row for sizing — the 40 A frame still gives you 39 A continuous, enough for a 40 A feeder if the load is under 39 A. The 3-pole body measures 70 mm deep by 76.2 mm wide by 130 mm high, a standard SENTRON 3VA footprint that fits the same DIN-rail or mounting-plate cutout as other 3VA frames up to 160 A.