The ABB S804C-C63 is a 4-pole miniature circuit breaker from the S800C series, rated at 63 A with a Trip Curve C characteristic. The interrupting rating is 15 kA at 230 V AC and 10 kA at 500 V DC, so it can safely clear a fault up to those levels without upstream damage — important for high-fault-capacity industrial panels.
Snap onto a DIN rail inside the enclosure; the 4-pole width occupies four modular spaces (72 mm at 18 mm per pole). Wire the line side to the top terminals, load side to the bottom — standard for panel builders.