Its interrupting capacity reaches 121 kA at 240 V, dropping to 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at both 500 V and 690 V — a curve that tells you the available fault current at your service voltage governs the selection, not the 40 A frame. The 70 mm depth and 101.6 mm width fit standard DIN-rail or panel-mount footprints; verify the 130 mm height clears your enclosure door or busbar shroud.
The 40 A rating holds to 50 °C ambient. At 55 °C it derates to 39 A, at 65 °C to 38 A, and at 70 °C to 37 A. If your panel runs hot — near a drive cabinet or in a roof-mounted enclosure — size the load to the 70 °C curve, not the nameplate. The 10.8 W maximum power loss is modest for a 4-pole 40 A frame, so internal cabinet heating from this breaker alone is negligible.
Absent features to note
If your specification requires any of those, this variant is not the one — you need the electronic-trip or accessory-equipped sibling in the SENTRON family.