The 5SL7263-8RC is a 2-pole miniature circuit breaker from Siemens, rated 63 A with a D-curve trip characteristic and a 10 kA breaking capacity at 415 V. The D-curve magnetic trip operates between 10x and 20x rated current, suitable for loads with high inrush such as motor starters and transformers.
The 2-pole form factor takes two module widths (about 36 mm) in the enclosure, so check your fill factor if you're packing a dense panel. Spring-cage terminals accept 0.75–25 mm² solid or stranded copper; strip length around 10–12 mm. Torque to 2.5 Nm for the line and load connections.