The 5SL6203-8CC: The 6 kA breaking capacity at 400 V tells you this breaker can safely interrupt a fault current up to 6,000 A without welding contacts or arcing over to adjacent devices. The 2-pole configuration switches both phase conductors simultaneously, which matters for single-phase line-to-neutral or line-to-line circuits where you want guaranteed isolation on both poles. The D-curve's magnetic trip range (10–20× In) means a 3 A breaker will hold through motor inrush that might hit 30–60 A for a few cycles, then trip on the thermal element for sustained overloads above 3 A.
RoHS compliant since June 1, 2013, and REACH candidate-list information is available on request. No UL or CSA listing is stated in the available documentation — this breaker is designed primarily for IEC markets (EN 60898 / IEC 60947-2). If your project requires UL 489 listing, you'll need to cross-reference to the Siemens 5SY or 5SU series, which carry UL/CSA marks for North American installations.