The 187 kA interrupting capacity at 240 V means it can safely break a fault current up to that level without the arc re-striking or the case rupturing; at 415 V and 440 V it still holds 121 kA, and at 500 V it's rated 75.6 kA. That's a high-rupturing-capacity breaker suited for installations with substantial available fault current — think industrial mains or large sub-distribution boards where the transformer is close.
Dimensions are 105 mm wide × 181 mm high × 86 mm deep — that's a standard 3-pole MCCB footprint for a 25 A frame, fitting most DIN-rail or direct-mount panel layouts without surprises.
Fault isolation and swap order
If you're swapping this into a live panel, note the ETU320 has no trip indicator and no undervoltage release — those are separate accessories if needed. Power loss is 0.6 W maximum, negligible for thermal budgeting.