The interrupting ratings tell the real story: 187 kA at 240 V, 121 kA at 415 V and 440 V, 79 kA at 500 V, and 3.4 kA at 690 V.
Trip unit and selectivity
The ETU350 is an electronic trip unit with LSI protection curves — long-time, short-time, and instantaneous — plus ground-fault capability if an external module is added (this variant ships without it). That short-time pickup and delay setting is the key for selective coordination downstream of a main breaker. You can set the short-time delay to ride through downstream faults and let the branch breaker clear first, keeping the rest of the panel live. The 63 A frame carries full current up to 55 °C before derating kicks in; at 70 °C it's still good for 53.55 A.
Panel fit and auxiliary contacts
That alarm contact is useful for feeding a remote annunciator or PLC input to distinguish a fault from a normal open. IP40 on the front face; acceptable for enclosed panel mounting.