Out here in the grease of a real plant floor, that 3 kA rating means it's sized for distribution boards downstream of a bigger main breaker, not for the service entrance where fault current runs higher. Rated IP20 with conductors connected, so it's strictly indoor panel use; keep it behind the enclosure door.
At 50 A, this breaker handles a 3-phase load up to about 35 kW at 400 V, assuming a typical power factor. For comparison, the same breaker typically carries a higher kA rating per EN 60898 for residential use, but the 3 kA figure here is the one that governs in industrial panels where IEC 60947-2 applies. The sealable design lets you lock the toggle in the off position for lockout/tagout — a detail that matters when you're writing a safe-work procedure.