The Siemens 5SY4263-5 SENTRON miniature circuit breaker is a 2-pole unit rated 63 A at 35 °C with a Class A tripping characteristic — that's a fast response typical for resistive loads and general distribution, not motor starting. Temperature derating is explicit: at 60 °C ambient the continuous current drops to 50.65 A, so if the panel runs hot, size upstream accordingly.
The 5SY4263-5 is specified to IEC/EN 60898-1 and IEC/EN 60947-2 / UL1077, halogen-free and silicon-free, with IP20 protection when conductors are connected. Compliance documentation (declaration of conformity, RoHS/REACH) is standard for the Siemens SENTRON line. For a BOM line calling for a 63 A 2-pole Class A MCB, this part fits without substitution concern.