The Siemens 5SL3163-7MB is a 1-pole SENTRON miniature circuit breaker rated 63 A at 400 V AC with a C tripping characteristic and a 4.5 kA breaking capacity per EN 60898. This is an active-production part, so it's a straightforward BOM-line fill for residential and light-commercial distribution panels where you need a 63 A branch circuit protector on a single phase.
The C-curve means the magnetic trip kicks in at 5 to 10 times rated current — 315 to 630 A for this 63 A unit — so it handles motor inrush and transformer energization without nuisance tripping, unlike a B-curve that would trip at 3 to 5×. That makes it the right choice for mixed loads with moderate starting currents in residential or light-commercial infrastructure panels. At 4.5 kA per EN 60898, this breaker can safely interrupt a fault current up to 4.5 kA at 400 V AC. If your panel's fault level exceeds that, you'd need the 5SY series (6 kA or 10 kA) or a current-limiting upstream device. The 18 mm width (1 width unit) means it snaps into any standard DIN-rail distribution board and occupies a single module position.
Terminals accept 0.75 to 25 mm² solid or stranded copper — covers everything from a 1.5 mm² lighting circuit tail up to a 16 mm² feeder for a 63 A submain. Mounting position is any orientation, so it works in horizontal busbar arrangements or vertical DIN-rail layouts without derating.