At 415 V the rating holds at 242 kA, dropping to 187 kA at 500 V and 7.5 kA at 690 V, so the voltage class of your installation determines which breaking capacity applies. The 400 A rating holds flat through 50 °C; above that it derates to 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. It ships without auxiliary switches or ground-fault monitoring.
Dimensions are 138 mm wide, 248 mm high, and 110 mm deep — a standard 3-pole MCCB footprint for Siemens SENTRON 3VA frames. The depth of 110 mm (4.33 in) is the projection from the mounting surface to the front of the breaker; verify gland-plate clearance if the panel has a shallow door or rear-mounted buswork. Power dissipation at rated load is 98.5 W maximum.