The Siemens 5SY4263-8CV is a 2-pole miniature circuit breaker with a D63 tripping characteristic and a rated breaking capacity of 15 kA at 400 V AC.
Panel integration
Snap-on DIN rail mount, standard 2-pole width. The 15 kA Icu at 400 V gives selectivity headroom downstream of a 25 kA main breaker — useful in a sub-distribution board feeding motor control centers. Terminal capacity accepts up to 25 mm² conductor, enough for the 63 A feed.