Rated at 125 A continuous at 40 °C, it's meant for a main feeder or a large downstream branch in a distribution panel.
How the ratings matter on the route
At 240 V it's rated 187 kA — that's a very high figure, typical for a main breaker close to a transformer. At 415 V it's still 121 kA, at 440 V it's 75.6 kA, and at 500 V and 690 V it drops to 17 kA. The continuous current rating is temperature-dependent. At 55 °C it derates to 122 A, at 60 °C to 120 A, at 65 °C to 117 A, and at 70 °C to 114 A.
It bolts into a panel on a mounting plate or a DIN rail adapter (the SENTRON 3VA series uses a common mounting base). The depth matters for enclosure depth selection: 70 mm plus wire bending space and the handle clearance means a 200 mm deep enclosure is tight; 300 mm is comfortable.