For selectivity coordination downstream of a larger feeder breaker, that 15 kA gives enough headroom to clear a bolted fault before the upstream device trips, keeping the rest of the panel live. In a 400 V distribution board, this matches the typical prospective fault current at a sub-distribution level.
Snap-on DIN rail mounting, standard 4-module width for a 4-pole MCB. The D13 curve and 15 kA rating suit it for motor branch circuits, welding equipment supplies, or any load with a high inrush-to-running-current ratio.