Breaking capacity is what earns this breaker its place in high-fault installations: 242 kA at 240 V AC, 187 kA at 415 V and 440 V, 121 kA at 500 V, and 3 kA at 690 V. The ETU320 release is an electronic trip unit — it gives you adjustable long-time, short-time, and instantaneous protection bands, which is what you want when coordinating with downstream breakers on a selective coordination study.
Footprint is 140 mm wide by 181 mm tall by 86 mm deep — a 4-pole frame that occupies roughly the same DIN-rail or mounting-plate real estate as a 160 A frame from the same SENTRON family. Maximum power dissipation is 0.84 W at rated current — negligible for panel heat-budget calculations, but it does mean the breaker runs cool even in a crowded enclosure.