Breaking capacity is 15 kA per EN 60898 and 25 kA per IEC 60947-2 / UL1077, so it handles fault currents up to that level without welding or cascading failure upstream — useful for industrial panels where the available fault current is known to be in that range.
Temperature derating — the real-world current
The 20 A rating holds at 35 °C ambient. Above that, the breaker derates linearly: 18.78 A at 40 °C, 18.14 A at 45 °C, 17.48 A at 50 °C, 16.8 A at 55 °C, and 16.08 A at 60 °C.
The 18 mm width means it takes up one slot in a standard distribution board. Sealable with a lockable cover if you need to prevent tampering.